10-K 1 lnt1231201510-k.htm 10-K

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 10-K

For the fiscal year ended December 31, 2015

or

For the transition period from to

This combined Form 10-K is separately filed by Alliant Energy Corporation, Interstate Power and Light Company and Wisconsin Power and Light Company. Information contained in the Form 10-K relating to Interstate Power and Light Company and Wisconsin Power and Light Company is filed by each such registrant on its own behalf. Each of Interstate Power and Light Company and Wisconsin Power and Light Company makes no representation as to information relating to registrants other than itself.

Securities registered pursuant to Section 12(b) of the Act:

Securities registered pursuant to Section 12(g) of the Act: None

Indicate by check mark if the registrants are well-known seasoned issuers, as defined in Rule 405 of the Securities Act.

Yes x No ¨

Indicate by check mark if the registrants are not required to file reports pursuant to Section 13 or Section 15(d) of the Act.

Yes ¨ No x

Indicate by check mark whether the registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrants were required to file such reports) and (2) have been subject to such filing requirements for the past 90 days. Yes x No ¨

Indicate by check mark whether the registrants have submitted electronically and posted on their corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that the registrants were required to submit and post such files). Yes x No ¨

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of the registrants’ knowledge, in definitive proxy or information statements incorporated by reference in Part III of this Form 10-K or any amendment to this Form 10-K. ¨

Indicate by check mark whether the registrants are large accelerated filers, accelerated filers, non-accelerated filers, or smaller reporting companies. See the definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act.

Indicate by check mark whether the registrants are shell companies (as defined in Rule 12b-2 of the Exchange Act). Yes ¨ No x

The aggregate market value of the voting and non-voting common equity held by nonaffiliates as of June 30, 2015:

Number of shares outstanding of each class of common stock as of January 29, 2016:

DOCUMENTS INCORPORATED BY REFERENCE

Portions of the Proxy Statement relating to Alliant Energy Corporation’s 2016 Annual Meeting of Shareowners are, or will be upon filing with the Securities and Exchange Commission, incorporated by reference into Part III hereof.

TABLE OF CONTENTS

DEFINITIONS

The following abbreviations or acronyms used in this Form 10-K are defined below:

FORWARD-LOOKING STATEMENTS

Statements contained in this Annual Report on Form 10-K that are not of historical fact are forward-looking statements intended to qualify for the safe harbors from liability established by the Private Securities Litigation Reform Act of 1995. These forward-looking statements can be identified as such because the statements include words such as “may,” “believe,” “expect,” “anticipate,” “plan,” “project, “will,” “projections,” “estimate,” or other words of similar import. Similarly, statements that describe future financial performance or plans or strategies are forward-looking statements. Such forward-looking statements are subject to certain risks and uncertainties that could cause actual results to differ materially from those expressed in, or implied by, such statements. Some, but not all, of the risks and uncertainties of Alliant Energy, IPL and WPL that could materially affect actual results include:

Alliant Energy, IPL and WPL each assume no obligation, and disclaim any duty, to update the forward-looking statements in this Annual Report on Form 10-K, except as required by law.

WEBSITE ACCESS TO REPORTS

Alliant Energy, IPL and WPL make their periodic and current reports, and amendments to those reports, available, free of charge, on Alliant Energy’s website at www.alliantenergy.com/investors on the same day as such material is electronically filed with, or furnished to, the SEC. Alliant Energy, IPL and WPL are not including the information contained on Alliant Energy’s website as a part of, or incorporating it by reference into, this Annual Report on Form 10-K.

PART I

This Annual Report on Form 10-K includes information relating to Alliant Energy, IPL and WPL (as well as Resources and Corporate Services). Where appropriate, information relating to a specific entity has been segregated and labeled as such. Unless otherwise noted, the information herein excludes discontinued operations for all periods presented.

A. GENERAL

Alliant Energy was incorporated in Wisconsin in 1981 and maintains its principal executive offices in Madison, Wisconsin. Alliant Energy operates as a regulated investor-owned public utility holding company. Alliant Energy’s primary focus is to provide regulated electric and natural gas service to approximately 950,000 electric and approximately 410,000 natural gas customers in the Midwest through its two public utility subsidiaries, IPL and WPL. The primary first tier wholly-owned subsidiaries of Alliant Energy are: IPL, WPL, Resources and Corporate Services. A brief description of the primary first tier subsidiaries of Alliant Energy is as follows:

1. IPL - was incorporated in 1925 in Iowa as Iowa Railway and Light Corporation. IPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa. IPL provides utility services to incorporated communities as directed by the IUB and utilizes non-exclusive franchises, which cover the use of public right-of-ways for utility facilities in incorporated communities for a maximum term of 25 years. At December 31, 2015, IPL supplied electric and natural gas service to approximately 489,000 and 225,000 retail customers, respectively, in Iowa. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa. IPL is also engaged in the generation and distribution of steam for two customers in Cedar Rapids, Iowa. In 2015, 2014 and 2013, IPL had no single customer for which electric, gas, steam and/or other sales accounted for 10% or more of IPL’s consolidated revenues.

2. WPL - was incorporated in 1917 in Wisconsin as Eastern Wisconsin Electric Company. WPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin. WPL operates in municipalities pursuant to permits of indefinite duration and state statutes authorizing utility operation in areas annexed by a municipality. At December 31, 2015, WPL supplied electric and natural gas service to approximately 461,000 and 184,000 retail customers, respectively. WPL also sells electricity to wholesale customers in Wisconsin. In 2015, 2014 and 2013, WPL had no single customer for which electric, gas and/or other sales accounted for 10% or more of WPL’s consolidated revenues. WPL’s consolidated subsidiary, WPL Transco, holds Alliant Energy’s investment in ATC. Refer to Note 6(a) for further discussion of ATC.

3. RESOURCES - was incorporated in 1988 in Wisconsin. In 2008, Resources was converted to a limited liability company. Alliant Energy’s non-regulated investments are organized under Resources. Refer to “Information Relating to Non-regulated Operations” for additional details.

4. CORPORATE SERVICES - was incorporated in 1997 in Iowa. Corporate Services provides administrative services to Alliant Energy, IPL, WPL and Resources.

Refer to Note 17 for further discussion of business segments, which information is incorporated herein by reference.

B. INFORMATION RELATING TO ALLIANT ENERGY ON A CONSOLIDATED BASIS

1. EMPLOYEES - At December 31, 2015, Alliant Energy’s consolidated subsidiaries had the following full- and part-time employees:

At December 31, 2015, Alliant Energy employees covered by collective bargaining agreements were as follows:

2. CAPITAL EXPENDITURE AND INVESTMENT PLANS - Refer to “Liquidity and Capital Resources” in MDA for discussion of anticipated construction and acquisition expenditures for 2016 through 2019.

3. REGULATION - Alliant Energy, IPL and WPL are subject to regulation by various federal, state and local agencies. The following includes the primary regulations impacting Alliant Energy’s, IPL’s and WPL’s businesses.

FERC -

Public Utility Holding Company Act of 2005 - Alliant Energy is registered with FERC as a public utility holding company, pursuant to the Public Utility Holding Company Act of 2005, and is required to maintain certain records and to report certain transactions involving its public utilities, service company and other entities regulated by FERC. Corporate Services, IPL and WPL are subject to regulation by FERC under the Public Utility Holding Company Act of 2005 for various matters including, but not limited to, affiliate transactions, public utility mergers, acquisitions and dispositions, and books, records and accounting requirements.

Energy Policy Act - The Energy Policy Act requires creation of an Electric Reliability Organization to provide oversight by FERC. FERC designated North American Electric Reliability Corporation as the overarching Electric Reliability Organization. Midwest Reliability Organization, which is a regional member of North American Electric Reliability Corporation, has direct responsibility for mandatory electric reliability standards for IPL and WPL.

Federal Power Act - FERC also has jurisdiction, under the Federal Power Act, over certain electric utility facilities and operations, electric wholesale and transmission rates, dividend payments, issuance of IPL’s securities, and accounting practices of Corporate Services, IPL and WPL.

Electric Wholesale Rates - IPL and WPL have received wholesale electric market-based rate authority from FERC. Market-based rate authorization allows for wholesale sales of electricity within the MISO market and in transactions directly with third parties, based on the market value of the transactions. IPL and WPL also have FERC-approved cost-of-service based rates related to the provision of firm full- and partial-requirement wholesale electric sales. Both IPL’s and WPL’s wholesale cost-of-service tariffs are formula-based tariffs that allow for true-ups to actual costs, including fuel costs.

Electric Transmission Rates - FERC regulates the rates charged for electric transmission facilities used in interstate commerce. Neither IPL nor WPL own or operate electric transmission facilities; however, both IPL and WPL pay for the use of the interstate electric transmission system based upon FERC-regulated rates. IPL and WPL rely primarily on the use of the ITC and ATC transmission systems, respectively. Due to the formula rates used by ITC and ATC to charge their customers and possible future changes to these rates, there is uncertainty regarding IPL’s and WPL’s future electric transmission service expense. Refer to “Other Future Considerations” in MDA for further discussion of electric transmission service expense.

Natural Gas Act - FERC regulates the transportation and sale for re

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You should carefully consider each of the risks described below relating to Alliant Energy, IPL and WPL, together with all of the other information contained in this combined Annual Report on Form 10-K, before making an investment decision with respect to our securities. If any of the following risks develop into actual events, our business, financial condition or results of operations could be materially and adversely affected and you may lose all or part of your investment.

Our business is significantly impacted by government legislation, regulation and oversight - We are subject to extensive regulation by federal and state regulatory authorities, which significantly influences our operations and our ability to timely recover costs from customers and earn appropriate rates of return. In particular, regulatory authorities with jurisdiction over public utilities, including the IUB, the PSCW, the MPUC and FERC, regulate many aspects of our operations. Our operations are also subject to oversight and monitoring by organizations such as the North American Electric Reliability Corporation, the Pipeline and Hazardous Materials Safety Administration, and the Midcontinent Independent System Operator, Inc. Operations impacted by these regulatory authorities and organizations include: the amount and timing of changes to rates charged to our customers; rates of return of IPL, WPL and ATC; our ability to site and construct new generating facilities, such as the natural gas-fired generating facilities in Marshalltown, Iowa and Beloit, Wisconsin, and future renewable energy projects, projects to utilize our remaining available wind sites, and the amount of costs associated therewith that may be recovered from customers; the installation of environmental controls and the amount of costs for the construction and maintenance of such equipment that may be recovered from customers; our ability to decommission generating facilities and recover the costs incurred to decommission the facilities and the remaining carrying value of such facilities; our ability to site and construct new natural gas pipelines; our ability to recover costs to upgrade our gas distribution system to comply with the anticipated Pipeline and Hazardous Materials Safety Administration requirements that have not yet been finalized; the amount of certain sources of energy we must use, such as renewable sources; our ability to purchase generating facilities and the amount of costs associated therewith that may be recovered from customers; our ability to sell utility assets and any conditions placed upon the sale of such assets; the rates paid to transmission operators and how those costs are recovered from customers; our ability to enter into purchased power agreements, the amount of costs associated therewith, and how those costs are recovered from customers; resource adequacy requirements, energy capacity standards, what forms of energy are considered when determining whether we meet those standards, and when new facilities such as IPL’s Marshalltown Generating Station and WPL’s proposed Riverside Energy Center expansion may be fully credited with energy capacity; the allocation of expenditures by transmission companies on transmission network upgrades and our ability to recover costs associated therewith from customers; reliability; safety; the issuance of securities; accounting matters; and transactions between affiliates. Failure to obtain approvals from regulatory authorities and organizations for any of these matters, failure to receive approvals in a timely manner, or receiving approvals with uneconomical conditions may adversely impact our ability to achieve our strategic plan, cause us to record an impairment of our assets, and/or have a material adverse impact on our financial condition and results of operations.

These regulatory authorities and organizations are also empowered to impose financial penalties and other sanctions if we are found to have violated statutes and regulations governing utility operations. While we believe we comply in all material

respects with applicable laws and regulations governing us, state or federal agencies may not agree and may find that we violated a law or regulation. Such a finding could cause fines or penalties or could require us to implement new compliance programs, which could increase our costs of compliance and may adversely impact our financial condition and results of operations.

Our utility financial condition is influenced by how regulatory authorities establish the rates we can charge our customers, our authorized rates of return and common equity levels, and the amount of deferred costs that may be recovered from customers. Our ability to timely obtain rate adjustments to earn authorized rates of return depends upon timely regulatory action under applicable statutes and regulations, and we cannot assure that rate adjustments will be obtained or authorized rates of return on capital will be earned. In future rate cases, IPL and WPL may not receive an adequate amount of rate relief to recover all costs and earn their authorized rates of return, rates may be reduced, rate refunds may be required, rate adjustments may not be approved on a timely basis, costs may not be otherwise recovered through rates, future rates may be temporarily frozen (as is the case for IPL’s and WPL’s retail electric base rates and WPL’s gas base rates through the end of 2016) and authorized rates of return on capital may be reduced. As a result, we may experience adverse impacts on our financial condition and results of operations.

We are subject to a wide variety of statutes, regulations and rules for energy market operations, grid management and reliability, including and in addition to those described above, which are constantly changing. State and federal election results may serve as a catalyst for legislative and regulatory changes. Changes in statutes, regulations and rules or the imposition of additional regulations and rules may require us to incur additional costs or change business operations or our business plan, which may have an adverse impact on our financial condition and results of operations.

Provisions of the Wisconsin Utility Holding Company Act limit our ability to invest in non-utility activities. Takeover attempts by potential purchasers who might be willing to pay a premium for our stock are also limited by certain provisions of the Wisconsin Utility Holding Company Act and the delays and conditions that generally result from the requirement that regulatory authorities approve such a transaction. During this time of industry change driven by technology and changing customer expectations, intentional or inadvertent policy changes could impact our business model competitiveness and accordingly our financial results.

Large construction projects are subject to delays and cost increases that may not be recovered from customers - Our strategic plan includes constructing natural gas-fired generating facilities, constructing renewable generating facilities, installing environmental control equipment at our newer and more efficient coal-fired generating facilities, and making other large-scale improvements to such generating facilities and large-scale additions and upgrades to our electric and gas distribution systems. These large construction projects are subject to various risks that could cause costs to increase or cause delays in completion. These risks include changes in costs of materials, equipment, commodities, fuel or labor; shortages in materials, equipment and qualified labor; changes to the scope or timing of the projects; general contractors or subcontractors not performing as required under their contracts; the inability to agree to contract terms or disputes in contract terms; poor initial cost estimates; work stoppages; adverse weather conditions; the inability to obtain necessary permits in a timely manner; adverse interpretation or enforcement of permit conditions; changes in applicable laws or regulations; governmental actions; legal action; unforeseen engineering or technology issues; limited access to capital; and other adverse economic conditions. We may not be able to recover all costs for the projects in rates and face increased risk of potential impairment of our project investment if a construction project is not completed or is delayed, or final costs exceed the costs approved by our regulators, for example, if the Marshalltown Generating Station exceeds the cost cap approved by the IUB. Inability to recover costs, or inability to complete the project in a timely manner, could adversely impact our financial condition and results of operations.

Demand for energy may decrease - Our results of operations are affected by the demand for energy in our service territories. We could lose customers, and therefore see lower demand for energy, due to economic conditions, customers constructing their own generation facilities, higher costs and rates charged to customers, or loss of service territory or franchises. Communities in our service territory have considered municipalization of electric or gas systems, which, if successful, could reduce the number of customers we serve, reducing the demand for our energy. Further, the energy conservation and technological advances that increase energy efficiency may temporarily or permanently reduce the demand for energy products. In addition, state and/or federal regulations require mandatory conservation measures, which would reduce the demand for energy. We may lose wholesale customers in addition to Jo-Carroll Energy, Inc., WPPI Energy and Great Lakes Utilities who have provided us notice of their intent to terminate their wholesale power supply agreements. Continuing technology improvements, tax incentives, regulatory developments and customer concern regarding their environmental and carbon footprint are making customer- and third party-owned generation technologies such as solar systems, wind turbines, microturbines and battery storage systems more cost effective, attractive and feasible for more of our

customers. As more customers utilize their own generation, demand for energy from us may decline and negatively impact the affordability of our services for remaining customers. Future economic growth may not create enough growth for us to replace the lost energy demand from these customers. The loss of customers, the inability to replace those customers with new customers, and the decrease in demand for energy could negatively impact our financial condition and results of operations.

Regional and national economic conditions could have an unfavorable impact on us - Our utility and non-regulated businesses follow the economic cycles of the customers we serve and credit risk of counterparties we do business with. Adverse economic conditions in our service territories can adversely affect the financial condition of our customers and reduce their demand for electricity and natural gas. Reduced volumes of electricity and natural gas sold, or the inability to collect unpaid bills from our customers from deterioration in national or regional economic conditions, could adversely impact our financial condition and results of operations.

Our operating results may fluctuate on a seasonal and quarterly basis and can be adversely affected by the impacts of weather - Our electric and gas utilities are seasonal businesses and temperature patterns can have a material impact on their operating performance. Demand for electricity is greater in the summer months associated with higher air conditioning needs. In addition, market prices for electricity generally peak in the summer due to the higher demand. Conversely, demand for natural gas depends significantly upon temperature patterns in winter months due to heavy use in residential and commercial heating. As a result, our overall operating results in the future may fluctuate substantially on a seasonal basis. In addition, we have historically generated less revenues and income when temperatures are warmer in the winter and/or cooler in the summer. Thus, unusually mild winters and/or summers could have an adverse effect on our financial condition and results of operations.

We are subject to numerous environmental laws and regulations, compliance with which could be difficult and costly, and pursuant to which we could incur material liabilities - We are subject to environmental laws and regulations that affect many aspects of our past, present and future operations. The environmental laws and regulations govern air emissions, ambient air quality standards, water quality, cooling water intake structures, wastewater discharges, the generation, transport and disposal of coal combustion residuals and other solid wastes and hazardous substances, clean-up of contaminated sites, protection of natural resources and wildlife. These laws and regulations require us to obtain and comply with a wide variety of environmental registrations, licenses, permits, inspections and other approvals, which are subject to renewal proceedings and legal challenges. Environmental laws and regulations can also require us to restrict or limit the output of certain facilities or to combust certain fuels, to install environmental controls and implement operational practices at our facilities, manage generation system dispatch within emissions limitations and constraints, clean up spills and correct environmental hazards and other contamination. We may be required to pay all or a portion of the costs to remediate (i.e., clean-up) sites where our past activities, or the activities of certain other parties, caused environmental contamination, including lakebeds, sites of manufactured gas plants operated by our predecessors and sites where asbestos was used in the past. Compliance with these regulations can significantly increase capital spending, operating costs and plant down-times, and can negatively affect the affordability of our services for customers. We cannot predict with certainty the amount and timing of all future expenditures (including the potential or magnitude of any fines or penalties, including the severity of any restriction on our operations) necessary to comply with, or as a result of liabilities under, these environmental laws and regulations, although we expect the expenditures to be material.

We are subject to Consent Decrees between each of IPL and WPL and various environmental agencies and organizations, which resolved environmental claims related to air emissions at certain coal-fired generating facilities. The Consent Decrees require construction of specific environmental controls equipment, establish emission rate limits, require retirement or fuel switching of certain facilities, and require IPL and WPL to complete certain environmental mitigation projects.

Although we believe we comply in all material respects with currently applicable environmental laws, regulations, and the Consent Decrees, we may be subject to regulatory enforcement action by state or federal agencies should we operate out of compliance. In some instances, complying with certain environmental regulations may not be sufficient to satisfy the obligations of the Consent Decrees or other operating regulations discussed earlier. In addition, citizen groups and private individuals may bring legal action against regulatory agencies or bring citizen enforcement actions against us claiming that the environmental requirements are not being sufficiently enforced by regulatory agencies. For example, the Consent Decrees resulted from allegations originally raised by the Sierra Club that IPL and WPL violated various provisions of the Clean Air Act. If we are unsuccessful defending or settling such litigation by governmental agencies, citizen groups, or individuals, we could be subject to restrictions or prohibitions on operating our generation facilities, costly upgrades to our generating facilities, payment of damages or fines, requirements to complete other beneficial environmental projects, and litigation costs, all of which could be material. An adverse result in such legal actions could have a material adverse impact

on our financial condition and results of operations. In addition, we may also be subject to third party environmental claims relating to property damage or personal injury that arise from our operations.

We are subject to existing and potential future governmental mandates to provide customers with renewable energy and energy conservation offerings. These mandates are designed in part to mitigate the potential environmental impacts of utility operations. Failure to meet the requirements of these mandates may result in fines or penalties, which could have a material adverse effect on our results of operations. If our regulators do not allow us to recover all or a part of the costs incurred to comply with the mandates, it could have a material adverse effect on our results of operations.

Existing environmental laws or regulations may be revised and new laws or regulations seeking to protect the environment and natural resources may be adopted or become applicable to us. Areas in our service territories that are currently attainment areas under National Ambient Air Quality Standards could be designated as non-attainment areas due to new air monitoring results or more stringent air quality standards. These revised and new laws or regulations and any areas in our service territories designated as non-attainment may require regulation of hazardous air pollutants including mercury, nitrogen oxide, sulfur dioxide, carbon dioxide (CO2) and other greenhouse gases (GHG) emissions, particulate matter, coal ash and other coal combustion products, wastewater discharges, cooling water intake structures, and threatened, endangered or invasive species. Federal and state election results may serve as a catalyst for regulatory changes. Such changes could materially increase our cost of compliance. Our strategic plan was developed in part to comply with expected environmental laws and regulations as we anticipate they will be finally adopted. Revision of existing environmental laws or regulations may cause: (1) state utility commissions to not approve our plans to install environmental controls at our existing generating facilities or not allow us to recover costs of such projects; (2) state utility commissions to not approve costs of emission allowances purchased to comply with environmental regulations that are no longer applicable to our operations; (3) co-owners in our jointly-owned facilities to not agree with our decision to move forward with and the timing of these projects; or (4) our current plans and/or past actions to not meet new requirements. These outcomes could have a material adverse effect on our financial condition and results of operations.

Actions related to global climate change and reducing GHG emissions could negatively impact us - The primary GHG emitted from our utility operations is CO2 from combustion of fossil fuels at our electric generating facilities, which are primarily fossil-fueled facilities. We could incur costs or other obligations to comply with any GHG regulations that are adopted in the future, and could become the target of legal claims or challenges, because generating electricity using fossil fuels emits CO2 and other GHGs. In 2013, a series of actions were announced to reduce carbon emissions, prepare the U.S. for the impacts of climate change, and lead international efforts to address climate change. In 2015, the U.S. joined a global agreement that commits participating countries to setting nationally determined climate targets to reduce greenhouse gas emissions and establishes a framework for reporting progress towards achieving these goals.

The EPA has proposed and adopted regulations governing GHG emissions that are expected to impact our operations. In October 2015, the EPA published regulations governing GHG emissions from new generating facilities, which would impact IPL’s Marshalltown Generating Station in Iowa and WPL’s proposed Riverside Energy Center expansion in Wisconsin. In October 2015, the EPA published regulations under Clean Air Act Section 111(d) to reduce CO2 emissions from existing fossil-fueled electric generating facilities, otherwise known as the Clean Power Plan. These EPA regulations are based on broad measures to lower CO2 emissions, which could impact the dispatch of existing fossil-fueled generating facilities and the fuel mix used to generate electricity, and require other actions in order to achieve CO2 emission reduction goals including fossil-fueled generating unit heat rate improvements, expansion of renewable energy resources and demand-side energy efficiency measures. The EPA’s GHG regulations are currently subject to litigation making the final form of the GHG emissions regulations uncertain. As a result of this uncertainty, strategies to comply with the regulations, including available control technologies or other allowed compliance measures, are unpredictable and we cannot provide any assurance regarding the potential impacts these regulations would have on our operations. The impacts of these regulations could have a material adverse impact on our financial condition and results of operations.

Threats of terrorism and catastrophic events that could result from terrorism may impact our operations in unpredictable ways - We are subject to direct and indirect effects of terrorist threats and activities. Generation, transmission and distribution facilities, in general, have been identified as potential targets of physical attacks. Physical attacks on transmission and distribution facilities that appeared to be terrorist-style attacks have occurred in the recent past. The risks posed by such attacks could include, among other things, the inability to generate, purchase or distribute electric energy or obtain fuel sources, the increased cost of security and insurance, the disruption of, volatility in, or other effects on capital markets, and a decline in the economy within our service territories, all of which could adversely impact our financial condition and results of operations. In addition, the cost of repairing damage to our facilities and infrastructure due to acts of

terrorism, and the loss of revenue if such events prevent us from providing utility service to our customers, could adversely impact our financial condition and results of operations.

A cyber attack may disrupt our operations or lead to a loss or misuse of confidential and proprietary information or potential liability - We operate in an industry that requires the continuous use and operation of sophisticated information technology systems and network infrastructure. Cyber attacks targeting our electronic control systems used at our generating facilities and for electric and gas distribution systems, such as recently allegedly occurred in Ukraine, could result in a full or partial disruption of our electric and/or gas operations. Any disruption of these operations could result in a loss of service to customers and a significant decrease in revenues, as well as significant expense to repair system damage and remedy security breaches. We have instituted certain safeguards to protect our operational systems and information technology assets. FERC, through the North American Electric Reliability Corporation, requires certain safeguards be implemented to deter cyber attacks. The safeguards we have may not always be effective due to the evolving nature of cyber attacks and cyber security. We cannot guarantee that such protections will be completely successful in the event of a cyber attack. If the technology systems were to fail or be breached by a cyber attack or a computer virus, and not be recovered in a timely fashion, we may be unable to fulfill critical business functions and confidential data could be compromised, adversely impacting our financial condition and results of operation.

In addition, in the ordinary course of business, we collect and retain sensitive information including personal information about our customers, shareowners and employees. In some cases, we outsource administration of certain functions to vendors that could be targets of cyber attacks. For example, we outsource administration of our employee health insurance to Anthem. Anthem was the target of a cyber attack in 2014. Any theft, loss and/or fraudulent use of customer, shareowner, employee or proprietary data as a result of a cyber attack could subject us to significant litigation, liability and costs, as well as adversely impact our reputation with customers and regulators, among others.

We may not be able to fully recover costs related to commodity prices - The prices that we may obtain for electric energy may not compensate for changes in delivered coal, natural gas or electric energy spot-market costs, or changes in the relationship between such costs and the market prices of electric energy. As a result, we may be unable to pass on the changes in costs to our customers, especially at WPL where we do not have a retail electric automatic fuel cost adjustment clause, which would allow for more consistent and timely cost recovery.

We are exposed to changes in the price and availability of coal because a large portion of the electricity generated by us is from our coal-fired generating facilities. We have contracts of varying durations for the supply and transportation of coal for most of our generating capability, but as these contracts end or otherwise are not honored, we may not be able to purchase coal on terms as favorable as the current contracts. Further, we currently rely on coal primarily from the Powder River Basin in Wyoming and any disruption of coal production in, or transportation from, that region, including due to bankruptcy of coal mining companies, may cause us to incur additional costs which may not be fully recovered through rates. Increases in prices and costs due to disruptions that are not fully and timely recovered in rates may adversely affect our financial condition and results of operations.

We are exposed to changes in the price and availability of natural gas. In addition to supplying natural gas to our natural gas customers, we also have responsibility to supply natural gas to certain natural gas-fired electric generating facilities that we own. Our strategic plan includes increasing our reliance on natural-gas fired electric generating facilities, particularly the new facilities planned in Marshalltown, Iowa and Beloit, Wisconsin, and coal-fired facilities expected to switch from coal to natural gas as the primary fuel type. This increases our exposure to market prices of natural gas, which have remained low recently, but have been volatile in the past. We have natural gas supply contracts in place, which are generally short-term in duration. The natural gas supply commitments are either fixed price in nature or market-based. As some of the contracts are market-based, and some of the contracts are short-term, we may not be able to purchase natural gas with terms and prices as favorable as the current contracts. Natural gas prices may increase due to disruption of production or transportation of natural gas, failure to drill new wells and reduced supply generally, or regulatory developments that increase the cost of natural gas extraction methods, including fracking. Price increases may cause us to incur additional costs to purchase natural gas, which may not be fully recovered through rates and may adversely impact our financial condition and results of operations.

We may not be able to fully recover higher transmission costs related to changing transmission reliability requirements - Both IPL and WPL pay for the use of the interstate electric transmission system that they do not own or control. Rates charged to IPL and WPL for such transmission service are regulated by FERC. FERC also regulates transmission owners’ operations in order to support the reliability of the transmission network. Changes are occurring in the transmission network, which are necessary to, among other things, accommodate renewable energy and the decommissioning

of older coal-fired generating facilities and prepare for potential compliance with future GHG regulations. These changes include socializing certain transmission network upgrades and system support resource payments, which may increase transmission costs to IPL and WPL. The prices that IPL and WPL charge for electric energy may not totally compensate for the increase in such transmission costs. We may not be able to fully pass on the increases in such transmission costs to our customers. In addition, if the transmission rider at IPL is amended or removed, we may not be able to recover IPL’s full transmission costs. Inability to fully recover transmission costs in a timely manner may adversely impact our financial condition and results of operations.

We are dependent on the capital markets and could be negatively impacted by disruptions in the capital markets - Successful implementation of our strategic plan and other long-term business strategies is dependent upon our ability to access the capital markets under competitive terms and rates. We have forecasted capital expenditures of approximately $5 billion over the next four years. Disruption, uncertainty or volatility in those markets could increase our cost of capital or limit the availability of capital. Disruptions could be caused by Federal Reserve policies and actions, currency concerns, economic downturn or uncertainty, monetary policies, a negative view of the utility industry or our company, failures of financial institutions, U.S. debt management concerns, U.S. debt limit and budget debates including government shutdowns, European and worldwide sovereign debt concerns, other global or geopolitical events, or other factors. Any disruptions could adversely impact our ability to implement our strategic plan.

We rely on our strong credit ratings to access the credit markets. If our credit ratings are downgraded for any reason, we could pay higher interest rates in future financings, the pool of potential lenders could be reduced, borrowing costs under existing credit facilities could increase, our access to the commercial paper market could be limited, or we could be required to provide additional credit assurance, including cash collateral, to contract counterparties. If our access to capital were to become significantly constrained or costs of capital increased significantly due to lowered credit ratings, prevailing industry conditions, regulatory constraints, the volatility of the capital markets or other factors, our financial condition and results of operations could be adversely affected.

We are subject to employee workforce factors that could affect our businesses - We are subject to employee workforce factors, including loss or retirement of key personnel, and the availability of, and our ability to recruit qualified personnel, which could affect our businesses and our financial condition and results of operations. Further, the majority of our key personnel are eligible to retire and our workforce includes a significant number of employees who are nearing retirement. We need employees with specialized and technical skills in order to achieve our strategic plan. It may be difficult to retain current employees with these specialized skills, especially as they near retirement, and it may be difficult to find new employees with the necessary skills. We are also subject to collective bargaining agreements with approximately 2,300 employees. Any work stoppage experienced in connections with negotiations of collective bargaining agreements could adversely affect our financial condition and results of operations as well as our ability to implement our strategic plan.

We face risks associated with operating electric and natural gas infrastructure - The operation of electric generating facilities involves many risks, including start-up risks, breakdown or failure of equipment, failure of generating facilities including wind turbines, the dependence on a specific fuel source, including the supply and transportation of fuel, the risk of performance below expected or contracted levels of output or efficiency, employee safety, operator error and compliance with mandatory reliability standards. The operation of our energy delivery infrastructure involves many risks including breakdown or failure of equipment and fires developing from our power lines. In addition, the North American transmission grid is highly interconnected and, in extraordinary circumstances, disruptions at particular points within the grid could cause an extensive power outage in our delivery systems. Increased utilization of customer- and third party-owned generation technologies could disrupt the reliability and balance of the electricity grid. Further, the transmission system in our utilities’ service territories is constrained, limiting the ability to transmit electric energy within our service territories. The transmission constraints could result in an inability to deliver energy from generating facilities, particularly wind generating facilities, to the national grid, or to access lower cost sources of electric energy. We also have obligations to provide electric service under regulatory requirements and contractual commitments. Failure to meet our service obligations could adversely impact our financial condition and results of operations.

The operation of our gas transmission and distribution infrastructure also involves many risks, such as leaks, explosions, mechanical problems and employee safety, which could cause substantial financial losses. These risks could result in loss of human life, particularly in highly populated areas, significant damage to property, environmental emissions, impairment of our operations and substantial losses to us. We are also responsible for compliance with new and changing mandatory reliability and safety standards, including anticipated new regulations under the Pipeline and Hazardous Materials Safety Administration. Our infrastructure is aging, which could impact safety and compliance with possible new regulations. Failure to meet these standards could result in substantial fines. Electric and gas infrastructure operations could be impacted

by future compliance with the Clean Power Plan. We also have obligations to provide service under regulatory requirements and contractual commitments. Failure to meet our service obligations could adversely impact our financial condition and results of operations.

We face risks associated with integration of a new customer billing and information system - We recently implemented a new customer billing and information system for IPL and WPL. This new customer billing and information system houses all customer records, and processes metering, billing and payment transactions. Integrating a new customer system is complex, costly and time consuming. If we do not successfully integrate the system and new related processes, or if it does not operate as intended, it could result in substantial disruptions to our business, including customer billings and collections, which could have a material adverse effect on our financial condition and results of operations.

Storms or other natural disasters may impact our operations in unpredictable ways - Storms and other natural disasters, including events such as floods, tornadoes, blizzards, ice storms, droughts, solar flares or pandemics may adversely impact our ability to generate, purchase or distribute electric energy or obtain fuel sources. We incur costs for preventive measures to replace, reinforce and modernize operating infrastructure that will provide for further grid resiliency. In addition, we could incur large costs to repair damage to our generating facilities and infrastructure, or costs related to environmental remediation, due to storms or natural disasters. Severe storms may also impact our natural gas infrastructure. The restoration costs may not be fully covered by insurance policies. Some costs may not be recovered in rates, including damaged assets, or there could be significant delays in cost recovery. Storms and natural disasters may prevent our customers from being able to operate or may significantly slow growth or cause a decline in the economy within our service territories. The reduced demand for energy could cause lower sales and revenues, which may not be replaced or recovered in rates. Any of these items could adversely affect our financial condition and results of operations.

We may incur material post-closing adjustments related to past asset and business divestitures - We previously sold certain non-regulated subsidiaries such as RMT, Inc. (RMT) and Whiting Petroleum Corporation (Whiting Petroleum), as well as regulated assets such as our recent sales of our Minnesota electric and natural gas distribution assets. We may continue to incur liabilities relating to our previous ownership of, or the transactions pursuant to which we disposed of, these subsidiaries and assets. For example, Alliant Energy continues to guarantee RMT’s performance obligations related to certain of RMT’s projects that were commenced prior to Alliant Energy’s sale of RMT. In addition, Alliant Energy Resources, LLC, as the successor to a predecessor entity that owned Whiting Petroleum, continues to guarantee the partnership obligations of an affiliate of Whiting Petroleum under general partnership agreements in the oil and gas industry, including liabilities with respect to the future abandonment of certain platforms off the coast of California and related onshore plant and equipment owned by the partnerships. Any potential liability under these guarantees may depend on a number of factors outside of our control, including the financial condition of RMT, Whiting Petroleum and/or their respective assignees. Any required payments on retained liabilities, guarantees or indemnification obligations with respect to RMT, Whiting Petroleum, the sales of our Minnesota electric and natural gas distribution assets, or other future asset or business divestitures, could have an adverse effect on our financial condition and results of operations.

We face risks related to non-regulated operations - We rely on our non-regulated operations for a portion of our earnings. If our non-regulated investments do not perform at expected levels, we could experience diminished earnings. Failure of our Transportation business to perform as expected could result in a material adverse impact on our financial condition and results of operations. In addition, Franklin County Wind LLC is a non-regulated subsidiary that operates a non-regulated 99 MW wind farm in Franklin County, Iowa, referred to as the Franklin County wind farm. The Franklin County wind farm’s electrical output is currently being sold into the general market at prevailing market prices. Additional decreases in forward electricity prices, or if there is reduced expected generation output from the facility if transmission upgrades in the region are not completed or do not result in expected decreased congestion, could trigger an impairment in the future. Such impairments could adversely impact our financial condition and results of operations. In addition, a variety of operating parameters, including adverse weather conditions, transmission constraints and breakdown or failure of equipment, could result in a material adverse impact on our financial condition and results of operations.

We are subject to limitations on our ability to pay dividends - Alliant Energy is a holding company with no significant operations of its own. Accordingly, the primary sources of funds for Alliant Energy to pay dividends to its shareowners are dividends and distributions from its subsidiaries, primarily its utility subsidiaries. Our subsidiaries are separate and distinct legal entities and have no obligation to pay any amounts to us, whether by dividends, distributions, loans or other payments. The ability of our subsidiaries to pay dividends or make distributions to us and, accordingly, our ability to pay dividends on Alliant Energy common stock will depend on regulatory limitations, earnings, cash flows, capital requirements and general financial condition of our subsidiaries. Our utilities have dividend payment restrictions based on the terms of any outstanding preferred stock and regulatory limitations applicable to them. If we do not receive adequate dividends and

distributions from our subsidiaries, then we may not be able to make, or may have to reduce, dividend payments on Alliant Energy common stock.

Changes to certain tax elections, tax regulations and future taxable income could negatively impact our financial condition and results of operations - We have significantly reduced our federal and state income tax obligations over the past few years through tax planning strategies and the extension of bonus depreciation deductions for certain expenditures for property. These tax planning strategies and extensions of bonus depreciation deductions have generated large annual taxable losses and tax credits over the past few years that have resulted in significant federal net operating losses and tax credit carryforwards. We plan to utilize these net operating losses and tax credit carryforwards in the future to reduce our income tax obligations. If we cannot generate enough taxable income in the future to utilize all of the net operating losses and tax credit carryforwards before they expire, we may incur material charges to earnings. If the IRS does not agree with the deductions resulting from our tax planning strategies, our financial condition and results of operations may be adversely impacted.

Our utility business currently operates wind generating facilities, which generate material production tax credits for us to use to reduce our federal tax obligations. The amount of production tax credits we earn is dependent on the level of electricity output generated by our wind farms and the applicable tax credit rate. A variety of operating and economic parameters, including significant transmission constraints, adverse weather conditions and breakdown or failure of equipment, could significantly reduce the production tax credits generated by our wind farms resulting in a material adverse impact on our financial condition and results of operations.

In addition, we have tax benefit riders in place in Iowa that provide billing credits to our customers. We have made certain assumptions regarding the timing of the tax benefit riders for accounting purposes. If those assumptions are not accurate, our results of operations and financial condition may be adversely impacted.

Lastly, if corporate tax rates or policies are changed with future federal or state legislation, we may be required to take material charges against earnings.

Our pension and other postretirement benefits plans are subject to investment and interest rate risk that could negatively impact our financial condition - We have pension and other postretirement benefits plans that provide benefits to many of our employees and retirees. Costs of providing benefits and related funding requirements of these plans are subject to changes in the market value of the assets that fund the plans. The funded status of the plans and the related costs reflected in our financial statements are affected by various factors, which are subject to an inherent degree of uncertainty, including economic conditions, financial market performance, interest rates, life expectancies and demographics. Recessions and volatility in the domestic and international financial markets have negatively affected the asset values of our pension plans at various times in the past. Poor investment returns or lower interest rates may necessitate accelerated funding of the plans in the future to meet minimum federal government requirements. Downward pressure on the asset values of our pension plans may require us to fund obligations earlier than originally planned, which could have an adverse impact on our financial condition and results of operations.

Energy industry changes could have a negative effect on our businesses - We operate in a highly regulated business environment. The advent of new and unregulated markets has the potential to significantly impact our financial condition and results of operations. The evolution of the wholesale and transmission markets has the potential to significantly increase costs of transmission, costs associated with inefficient generation dispatching, costs of participation in the new markets and costs stemming from estimated payment settlements. Competitive pressures, including advances in technology that reduce the costs of alternative methods of producing electric energy to a level that is competitive with that of current electric production methods, could result in our utilities losing market share and customers and incurring stranded costs (i.e., assets and other costs rendered unrecoverable through customer rates), which could be borne by our shareowners. Changes in technology could also alter the channels through which electric customers buy or utilize power, which could reduce the revenues or increase the expenses of our utility companies. Increased competition from any restructuring efforts in our primary retail electric service territories may have a significant adverse impact on our financial condition and results of operations.

None.

Alliant Energy - As a holding company, Alliant Energy doesn’t directly own any significant properties other than the stock of its subsidiaries. The principal properties of those subsidiaries are as follows:

IPL

Electric - At December 31, 2015, IPL’s EGUs by primary fuel type were as follows:

At December 31, 2015, IPL owned approximately 17,567 miles of overhead electric distribution line and 2,872 miles of underground electric distribution cable, as well as 573 substation distribution transformers, substantially all of which are located in Iowa.

Gas - IPL’s gas properties consist primarily of mains and services, meters, regulating and gate stations and other related transmission and distribution equipment. At December 31, 2015, IPL’s gas distribution facilities included approximately 5,119 miles of gas mains located in Iowa.

Other - IPL’s other property consists primarily of steam service assets, operating and storeroom facilities, vehicles, computer hardware and software, communication equipment and other miscellaneous tools and equipment.

WPL

Electric - At December 31, 2015, WPL’s EGUs by primary fuel type were as follows:

At December 31, 2015, WPL owned approximately 16,281 miles of overhead electric distribution line and 5,315 miles of underground electric distribution cable, as well as 302 substation distribution transformers, substantially all of which are located in Wisconsin. Refer to Notes 2 and 3 for discussion of Nelson Dewey Units 1 and 2 and Edgewater Unit 3, which were retired in 2015.

Gas - WPL’s gas properties consist primarily of mains and services, meters, regulating and gate stations and other related transmission and distribution equipment. At December 31, 2015, WPL’s gas distribution facilities included approximately 4,307 miles of gas mains located in Wisconsin.

Other - Refer to Note 10(b) for information regarding WPL’s lease of Sheboygan Falls from Resources’ Non-regulated Generation business. WPL’s other property consists primarily of operating and storeroom facilities, vehicles, computer hardware and software, communication equipment and other miscellaneous tools and equipment.

Resources - Resources’ principal properties included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2015 were as follows:

Non-regulated Generation - Includes Sheboygan Falls, a 347 MW, simple-cycle, natural gas-fired facility near Sheboygan Falls, Wisconsin that was placed in service in 2005 and is leased to WPL, and the 99 MW (60 Units) Franklin County wind farm in Franklin County, Iowa that was placed in service in 2012. Sheboygan Falls was accredited with 282 MW of generating capacity for MISO’s resource adequacy process for the planning period from June 2015 through May 2016.

Transportation - Includes a short-line railway in Iowa with 114 miles of railroad track, 13 active locomotives and 72 rail-cars; a barge terminal on the Mississippi River; and a coal terminal in Williams, Iowa.

Corporate Services - Corporate Services’ property included in “Property, plant and equipment, net” on Alliant Energy’s balance sheet at December 31, 2015 consisted primarily of computer software, the corporate headquarters building located in Madison, Wisconsin, and a new customer billing and information system for IPL and WPL, which was placed in service in 2015.

Alliant Energy - None.

IPL - None.

WPL - None.

Other - Alliant Energy, IPL and WPL are involved in legal and administrative proceedings before various courts and agencies with respect to matters arising in the ordinary course of business. Although unable to predict the outcome of these matters, Alliant Energy, IPL and WPL believe that final disposition of these actions will not have a material effect on their financial condition or results of operations.

None.

EXECUTIVE OFFICERS OF THE REGISTRANTS

None of the executive officers for Alliant Energy, IPL or WPL listed below are related to any member of the Board of Directors or nominee for director or any other executive officer. All of the executive officers have no definite terms of office and serve at the pleasure of the Board of Directors. The executive officers of Alliant Energy, IPL and WPL as of the date of this filing are as follows (numbers following the names represent the officer’s age as of the date of this filing):

Executive Officers of Alliant Energy

Executive Officers of IPL

Executive Officers of WPL

PART II

Stock Price - Alliant Energy’s common stock trades on the New York Stock Exchange under the symbol “LNT.” Quarterly sales price ranges and dividends with respect to Alliant Energy’s common stock were as follows:

Stock closing price at December 31, 2015: $62.45

Shareowners - At December 31, 2015, there were 28,294 holders of record of Alliant Energy’s common stock, including holders through Alliant Energy’s Shareowner Direct Plan. Alliant Energy is the sole common shareowner of all 13,370,788 and 13,236,601 shares of IPL and WPL common stock, respectively, currently outstanding. As a result, there is no established public trading market for the common stock of either IPL or WPL.

Dividends - In November 2015, Alliant Energy announced an increase in its targeted 2016 annual common stock dividend to $2.35 per share, which is equivalent to a quarterly rate of $0.5875 per share, beginning with the February 2016 dividend payment. The timing and amount of future dividends is subject to an approved dividend declaration from Alliant Energy’s Board of Directors, and is dependent upon earnings expectations, capital requirements, and general financial business conditions, among other factors.

Alliant Energy does not have any significant common stock dividend restrictions. Refer to Note 7 for information about IPL’s and WPL’s dividend restrictions and limitations on distributions to their parent company.

Common Stock Repurchases - A summary of Alliant Energy common stock repurchases for the quarter ended December 31, 2015 was as follows:

Other - Refer to “Security Ownership of Certain Beneficial Owners and Management and Related Stockholder Matters” in Item 12 for details of securities authorized for issuance under equity compensation plans.

Financial Information

Alliant Energy is the sole common shareowner of all 13,370,788 shares of IPL’s common stock outstanding. As such, earnings per share data is not disclosed herein.

Alliant Energy is the sole common shareowner of all 13,236,601 shares of WPL’s common stock outstanding. As such, earnings per share data is not disclosed herein.

This MDA includes information relating to Alliant Energy, IPL and WPL, as well as Resources and Corporate Services. Where appropriate, information relating to a specific entity has been segregated and labeled as such. The following discussion and analysis should be read in conjunction with the Financial Statements and Notes included in this report. Unless otherwise noted, all “per share” references in MDA refer to earnings per diluted share.

CONTENTS OF MDA

MDA consists of the following information:

EXECUTIVE SUMMARY

Description of Business

General - Alliant Energy is an investor-owned public utility holding company whose primary subsidiaries are IPL, WPL, Resources and Corporate Services. IPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Iowa. IPL also sells electricity to wholesale customers in Minnesota, Illinois and Iowa. WPL is a public utility engaged principally in the generation and distribution of electricity and the distribution and transportation of natural gas to retail customers in select markets in Wisconsin. WPL also sells electricity to wholesale customers in Wisconsin. At December 31, 2015, WPL and Resources, through their ownership interests in WPL Transco, in aggregate held an approximate 16% ownership interest in ATC, a transmission-only utility operating primarily in the Midwest. Resources is the parent company for Alliant Energy’s non-regulated businesses. Corporate Services provides administrative services to Alliant Energy and its subsidiaries. An illustration of Alliant Energy’s primary businesses is shown below.

Utilities and Corporate Services - IPL and WPL own a portfolio of EGUs located in Iowa, Wisconsin and Minnesota with a diversified fuel mix including coal, natural gas and renewable resources. The output from these EGUs, supplemented with purchased power, is used to provide electric service to approximately 950,000 electric customers in the upper Midwest. The utility business also procures natural gas from various suppliers to provide service to approximately 410,000 retail gas customers in the upper Midwest. Alliant Energy’s utility business is its primary source of earnings and cash flows. The earnings and cash flows from the utilities and Corporate Services business are sensitive to various external factors including, but not limited to, the amount and timing of rates approved by regulatory authorities, the impact of weather and economic conditions on electric and gas sales volumes and other factors listed in “Risk Factors” in Item 1A and “Forward-looking Statements.”

Non-regulated Business and Parent - Resources manages various businesses including Non-regulated Generation (Sheboygan Falls and the Franklin County wind farm), Transportation (short-line railway and barge transportation services) and several other modest investments.

Financial Results - Alliant Energy’s net income and EPS attributable to Alliant Energy common shareowners were as follows (dollars in millions, except per share amounts):

The table above includes EPS from continuing operations for utilities, ATC and Corporate Services, and non-regulated and parent, which are non-GAAP financial measures. Alliant Energy believes EPS from continuing operations for utilities, ATC and Corporate Services, and non-regulated and parent are useful to investors because they facilitate an understanding of segment performance and trends and provide additional information about Alliant Energy’s operations on a basis consistent with the measures that management uses to manage its operations and evaluate its performance.

Lower earnings from continuing operations in 2015 compared to 2014 was primarily due to higher electric transmission service expense at WPL; lower electric and gas sales attributed to milder temperatures in 2015; higher income tax, depreciation, interest and employee benefits-related expenses; losses on sales of IPL’s Minnesota electric and gas distribution assets in 2015; and lower earnings at Transportation. These items were partially offset by lower retail electric customer billing credits at IPL; lower energy efficiency cost recovery amortization at WPL; and capacity charges related to the IPL DAEC PPA in 2014.

Refer to “Results of Operations” for additional details regarding the various factors impacting earnings during 2015, 2014 and 2013.

2015 Overview - In 2015, Alliant Energy, IPL and WPL focused on achieving financial objectives and executing their strategic plan, including providing competitive value and exceptional service for their customers and finding innovative ways to operate the business more efficiently and provide flexible energy resources. Key developments in 2015 include the following:

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Quantitative and Qualitative Disclosures About Market Risk are reported in “Other Matters - Market Risk Sensitive Instruments and Positions” in MDA.

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Shareowners of

Alliant Energy Corporation

Madison, Wisconsin

We have audited the accompanying consolidated balance sheets of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, 2015 and 2014, and the related consolidated statements of income, common equity, and cash flows for each of the three years in the period ended December 31, 2015. Our audits also included the Company’s financial statement schedules listed in the Index at Item 15. These financial statements and financial statement schedules are the responsibility of the Company’s management. Our responsibility is to express an opinion on the financial statements and financial statement schedules based on our audits.

We conducted our audits in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether the financial statements are free of material misstatement. An audit includes examining, on a test basis, evidence supporting the amounts and disclosures in the financial statements. An audit also includes assessing the accounting principles used and significant estimates made by management, as well as evaluating the overall financial statement presentation. We believe that our audits provide a reasonable basis for our opinion.

In our opinion, such consolidated financial statements present fairly, in all material respects, the financial position of the Company as of December 31, 2015 and 2014, and the results of its operations and its cash flows for each of the three years in the period ended December 31, 2015, in conformity with accounting principles generally accepted in the United States of America. Also, in our opinion, such financial statement schedules, when considered in relation to the basic consolidated financial statements taken as a whole, present fairly, in all material respects, the information set forth therein.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States), the Company’s internal control over financial reporting as of December 31, 2015, based on the criteria established in Internal Control-Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission and our report dated February 24, 2016 expressed an unqualified opinion on the Company’s internal control over financial reporting.

/s/ DELOITTE & TOUCHE LLP

DELOITTE & TOUCHE LLP

Milwaukee, Wisconsin

February 24, 2016

ALLIANT ENERGY CORPORATION

CONSOLIDATED STATEMENTS OF INCOME

The accompanying Combined Notes to Consolidated Financial Statements are an integral part of these statements.

ALLIANT ENERGY CORPORATION

CONSOLIDATED BALANCE SHEETS

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None.

Alliant Energy’s, IPL’s and WPL’s management evaluated, with the participation of each of Alliant Energy’s, IPL’s and WPL’s CEO, CFO and Disclosure Committee, the effectiveness of the design and operation of Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures as of the end of the quarter ended December 31, 2015 pursuant to the requirements of the Securities Exchange Act of 1934, as amended. Based on their evaluation, the CEO and the CFO concluded that Alliant Energy’s, IPL’s and WPL’s disclosure controls and procedures were effective as of the end of the quarter ended December 31, 2015.

During the fourth quarter of 2015, WPL implemented a new customer billing and information system, which houses all customer records, and processes metering, billing and payment transactions. The new system more fully automates and improves the efficiency of WPL’s financial reporting process, and resulted in a material change in Alliant Energy’s and WPL’s internal control over financial reporting. Other than WPL’s new customer billing and information system, there was no change in Alliant Energy’s and WPL’s internal control over financial reporting that occurred during the quarter ended December 31, 2015 that has materially affected, or is reasonably likely to materially affect, Alliant Energy’s and WPL’s internal control over financial reporting. There was no change in IPL’s internal control over financial reporting that occurred during the quarter ended December 31, 2015 that has materially affected, or is reasonably likely to materially affect, IPL’s internal control over financial reporting.

MANAGEMENT’S ANNUAL REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

The management of Alliant Energy Corporation and subsidiaries (Alliant Energy) is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. Alliant Energy’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with accounting principles generally accepted in the United States of America.

Because of the inherent limitations of internal control over financial reporting, misstatements may not be prevented or detected on a timely basis. Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

Alliant Energy’s management assessed the effectiveness of Alliant Energy’s internal control over financial reporting as of December 31, 2015 using the criteria set forth in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this assessment, Alliant Energy’s management concluded that, as of December 31, 2015, Alliant Energy’s internal control over financial reporting was effective.

Deloitte & Touche LLP, Alliant Energy’s independent registered public accounting firm, has audited Alliant Energy’s internal control over financial reporting. That report is included herein.

/s/ Patricia L. Kampling

Patricia L. Kampling

Chairman, President and Chief Executive Officer

/s/ Thomas L. Hanson

Thomas L. Hanson

Senior Vice President and Chief Financial Officer

/s/ Robert J. Durian

Robert J. Durian

Vice President, Chief Accounting Officer and Controller

February 24, 2016

REPORT OF INDEPENDENT REGISTERED PUBLIC ACCOUNTING FIRM

To the Board of Directors and Shareowners of

Alliant Energy Corporation

Madison, Wisconsin

We have audited the internal control over financial reporting of Alliant Energy Corporation and subsidiaries (the “Company”) as of December 31, 2015, based on the criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. The Company’s management is responsible for maintaining effective internal control over financial reporting and for its assessment of the effectiveness of internal control over financial reporting, included in the accompanying Management’s Annual Report on Internal Control over Financial Reporting. Our responsibility is to express an opinion on the Company’s internal control over financial reporting based on our audit.

We conducted our audit in accordance with the standards of the Public Company Accounting Oversight Board (United States). Those standards require that we plan and perform the audit to obtain reasonable assurance about whether effective internal control over financial reporting was maintained in all material respects. Our audit included obtaining an understanding of internal control over financial reporting, assessing the risk that a material weakness exists, testing and evaluating the design and operating effectiveness of internal control based on the assessed risk, and performing such other procedures as we considered necessary in the circumstances. We believe that our audit provides a reasonable basis for our opinion.

A company’s internal control over financial reporting is a process designed by, or under the supervision of, the company’s principal executive and principal financial officers, or persons performing similar functions, and effected by the company’s board of directors, management, and other personnel to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles. A company’s internal control over financial reporting includes those policies and procedures that (1) pertain to the maintenance of records that, in reasonable detail, accurately and fairly reflect the transactions and dispositions of the assets of the company; (2) provide reasonable assurance that transactions are recorded as necessary to permit preparation of financial statements in accordance with generally accepted accounting principles, and that receipts and expenditures of the company are being made only in accordance with authorizations of management and directors of the company; and (3) provide reasonable assurance regarding prevention or timely detection of unauthorized acquisition, use, or disposition of the company’s assets that could have a material effect on the financial statements.

Because of the inherent limitations of internal control over financial reporting, including the possibility of collusion or improper management override of controls, material misstatements due to error or fraud may not be prevented or detected on a timely basis. Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

In our opinion, the Company maintained, in all material respects, effective internal control over financial reporting as of December 31, 2015, based on the criteria established in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission.

We have also audited, in accordance with the standards of the Public Company Accounting Oversight Board (United States), the consolidated financial statements and financial statement schedules as of and for the year ended December 31, 2015 of the Company and our report dated February 24, 2016 expressed an unqualified opinion on those financial statements and financial statement schedules.

/s/ DELOITTE & TOUCHE LLP

DELOITTE & TOUCHE LLP

Milwaukee, Wisconsin

February 24, 2016

MANAGEMENT’S ANNUAL REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

The management of Interstate Power and Light Company and subsidiary (IPL) is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. IPL’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with accounting principles generally accepted in the United States of America.

Because of the inherent limitations of internal control over financial reporting, misstatements may not be prevented or detected on a timely basis. Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

IPL’s management assessed the effectiveness of IPL’s internal control over financial reporting as of December 31, 2015 using the criteria set forth in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this assessment, IPL’s management concluded that, as of December 31, 2015, IPL’s internal control over financial reporting was effective.

This Annual Report on Form 10-K does not include an attestation report of IPL’s independent registered public accounting firm regarding IPL’s internal control over financial reporting. Management’s report was not subject to attestation by IPL’s independent registered public accounting firm pursuant to rules of the Securities and Exchange Commission that permit IPL to provide only management’s report in this Annual Report on Form 10-K.

/s/ Patricia L. Kampling

Patricia L. Kampling

Chairman and Chief Executive Officer

/s/ Thomas L. Hanson

Thomas L. Hanson

Senior Vice President and Chief Financial Officer

/s/ Robert J. Durian

Robert J. Durian

Vice President, Chief Accounting Officer and Controller

February 24, 2016

MANAGEMENT’S ANNUAL REPORT ON INTERNAL CONTROL OVER FINANCIAL REPORTING

The management of Wisconsin Power and Light Company and subsidiary (WPL) is responsible for establishing and maintaining adequate internal control over financial reporting, as such term is defined in Rules 13a-15(f) and 15d-15(f) under the Securities Exchange Act of 1934. WPL’s internal control over financial reporting is designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with accounting principles generally accepted in the United States of America.

Because of the inherent limitations of internal control over financial reporting, misstatements may not be prevented or detected on a timely basis. Also, projections of any evaluation of the effectiveness of the internal control over financial reporting to future periods are subject to the risk that the controls may become inadequate because of changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate.

WPL’s management assessed the effectiveness of WPL’s internal control over financial reporting as of December 31, 2015 using the criteria set forth in Internal Control - Integrated Framework (2013) issued by the Committee of Sponsoring Organizations of the Treadway Commission. Based on this assessment, WPL’s management concluded that, as of December 31, 2015, WPL’s internal control over financial reporting was effective.

This Annual Report on Form 10-K does not include an attestation report of WPL’s independent registered public accounting firm regarding WPL’s internal control over financial reporting. Management’s report was not subject to attestation by WPL’s independent registered public accounting firm pursuant to rules of the Securities and Exchange Commission that permit WPL to provide only management’s report in this Annual Report on Form 10-K.

/s/ Patricia L. Kampling

Patricia L. Kampling

Chairman and Chief Executive Officer

/s/ Thomas L. Hanson

Thomas L. Hanson

Senior Vice President and Chief Financial Officer

/s/ Robert J. Durian

Robert J. Durian

Vice President, Chief Accounting Officer and Controller

February 24, 2016

None.

PART III

The directors of Alliant Energy, IPL and WPL are the same, and therefore, the information required by Item 10 relating to directors and nominees for election of directors is the same for all registrants. The information required by Item 10 relating to directors and nominees for election of directors at the 2016 Annual Meeting of Shareowners, the timely filing of reports under Section 16 of the Securities Exchange Act of 1934, audit committees and audit committee financial experts, and Alliant Energy’s, IPL’s and WPL’s Code of Conduct is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years. The code of ethics, also referred to as the Code of Conduct, of Alliant Energy, IPL and WPL are the same. Information regarding executive officers of Alliant Energy, IPL and WPL may be found in Part I of this report under the caption “Executive Officers of the Registrants.”

The directors and executive officers of Alliant Energy, IPL and WPL for which compensation information must be included are the same. Therefore, the information required by Item 11 for each of Alliant Energy, IPL and WPL is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years.

ALLIANT ENERGY

Information regarding Alliant Energy’s equity compensation plans as of December 31, 2015 was as follows:

The remainder of the information required by Item 12 is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s fiscal year.

IPL AND WPL

None of IPL’s directors or executive officers own any shares of preferred stock in IPL. The remainder of the information required by Item 12 is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of IPL’s and WPL’s fiscal years.

The information required by Item 13 for each of Alliant Energy, IPL and WPL is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s, IPL’s and WPL’s fiscal years.

ALLIANT ENERGY

The information required by Item 14 is incorporated herein by reference to the relevant information in the 2016 Alliant Energy Proxy Statement, which will be filed with the SEC within 120 days after the end of Alliant Energy’s fiscal year.

IPL AND WPL

Each of IPL’s and WPL’s Audit Committee has adopted a policy that requires advance approval of all audit, audit-related, tax and other permitted services performed by the independent registered public accounting firm. The policy provides for pre-approval by the Audit Committee of specifically defined audit and non-audit services after the Audit Committee is provided with the appropriate level of details regarding the specific services to be provided. The policy does not permit delegation of the Audit Committee’s authority to management. In the event the need for specific services arises between Audit Committee meetings, the Audit Committee has delegated to the Chairperson of the Audit Committee authority to approve permitted services provided that the Chairperson reports any decisions to the Audit Committee at its next scheduled meeting. The principal accounting fees billed to Alliant Energy by its independent registered public accounting firm, all of which were approved in advance by the Audit Committee, directly related and allocated to IPL and WPL were as follows (in thousands):

IPL’s and WPL’s audit fees for 2015 and 2014 consisted of the respective fees billed for the audits of the financial statements of IPL and its subsidiary and WPL and its subsidiary, for reviews of financial statements included in Form 10-Q filings, and for services normally provided in connection with statutory and regulatory filings, such as financing transactions. IPL’s and WPL’s audit fees also included their respective portion of fees for the 2015 and 2014 audits of Alliant Energy’s financial statements and effectiveness of internal controls over financial reporting. IPL’s and WPL’s audit fees for 2015 also included fees billed for services related to a change in method of recording income taxes at IPL and WPL. IPL’s and WPL’s audit-related fees for 2015 and 2014 consisted of the fees billed for services rendered related to employee benefits plan audits and other attest services. All other fees for 2015 and 2014 for IPL and WPL consisted of license fees for accounting research software products and seminars. IPL and WPL did not have any tax fees for 2015 or 2014. The Audit Committee does not consider the provision of non-audit services by the independent registered public accounting firm described above to be incompatible with maintaining independence of the independent registered public accounting firm.

PART IV

Schedule I. Condensed Parent Company Financial Statements

Schedule II. Valuation and Qualifying Accounts and Reserves

NOTE: All other schedules are omitted because they are not applicable or not required, or because that required information is shown either in the financial statements or in the notes thereto.

SCHEDULE I - CONDENSED PARENT COMPANY FINANCIAL STATEMENTS

ALLIANT ENERGY CORPORATION (Parent Company Only)

CONDENSED STATEMENTS OF INCOME

The accompanying Notes to Condensed Financial Statements are an integral part of these statements.

ALLIANT ENERGY CORPORATION (Parent Company Only)

CONDENSED BALANCE SHEETS

The accompanying Notes to Condensed Financial Statements are an integral part of these statements.

ALLIANT ENERGY CORPORATION (Parent Company Only)

CONDENSED STATEMENTS OF CASH FLOWS

The accompanying Notes to Condensed Financial Statements are an integral part of these statements.

ALLIANT ENERGY CORPORATION

(Parent Company Only)

NOTES TO CONDENSED FINANCIAL STATEMENTS

Pursuant to rules and regulations of the SEC, the Condensed Financial Statements of Alliant Energy Corporation (Parent Company Only) do not reflect all of the information and notes normally included with financial statements prepared in accordance with GAAP. Therefore, these Condensed Financial Statements should be read in conjunction with the Financial Statements and related Notes included in Alliant Energy’s 2015 Form 10-K, Part II, Item 8, which is incorporated herein by reference.

In the Condensed Financial Statements of Alliant Energy Corporation (Parent Company Only), investments in subsidiaries are accounted for using the equity method.

Alliant Energy allocates income tax expense to its subsidiaries that are members of the group that file a consolidated or combined income tax return. In the fourth quarter of 2015, Alliant Energy changed its method of allocating income tax provisions and related deferred tax assets and liabilities to its subsidiaries from the parent-company-down approach to the modified separate return approach. The change was retrospectively applied to the Parent Company’s Condensed Financial Statements. This tax method change did not impact Alliant Energy’s consolidated financial statements. The change had no impact on Parent Company net income, but impacted the income tax provisions and the equity earnings from consolidated subsidiaries in the Parent Company Condensed Statements of Income, as well as investment in consolidated subsidiaries and deferred tax liabilities on the Parent Company Condensed Balance Sheets. Refer to Note 1(c) for additional information on the tax method change.

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet From the Assets to Which They Apply: