Item 14. PRINCIPAL ACCOUNTANT FEES AND SERVICES.

The Audit Committee of the UAL Board of Directors has adopted a policy on pre-approval of services of the Company's independent registered public accounting firm. As a wholly-owned subsidiary of UAL, United's audit services are determined by UAL. The policy provides that the Audit Committee shall pre-approve all audit and non-audit services to be provided to UAL and its subsidiaries and affiliates by its independent auditors. The process by which this is carried out is as follows:

For recurring services, the Audit Committee reviews and pre-approves the independent registered public accounting firm's annual audit services in conjunction with the annual appointment of the outside auditors. The reviewed materials include a description of the services along with related fees. The Audit Committee also reviews and pre-approves other classes of recurring services along with fee thresholds for pre-approved services. In the event that the additional services are required prior to the next scheduled Audit Committee meeting, pre-approvals of additional services follow the process described below.

Any requests for audit, audit related, tax and other services not contemplated with the recurring services approval described above must be submitted to the Audit Committee for specific pre-approval and cannot commence until such approval has been granted. Normally, pre-approval is provided at regularly scheduled meetings. However, the authority to grant specific pre-approval between meetings, as necessary, has been delegated to the Chair of the Audit Committee. The Chair must update the Audit Committee at the next regularly scheduled meeting of any services that were granted specific pre-approval.

On a periodic basis, the Audit Committee reviews the status of services and fees incurred year-to-date and a list of newly pre-approved services since its last regularly scheduled meeting. The Audit Committee has considered whether the 2019 and 2018 non-audit services provided by Ernst & Young LLP, the Company's independent registered public accounting firm, are compatible with maintaining auditor independence.

All of the services in 2019 and 2018 under the Audit Fees, Audit Related Fees, Tax Fees and All Other Fees categories below have been approved by the Audit Committee pursuant to paragraph (c)(7) of Rule 2-01 of Regulation S-X of the Exchange Act.

The aggregate fees billed for professional services rendered by the Company's independent auditors in 2019 and 2018 are as follows (in thousands):

Audit Fees. For 2019 and 2018, audit fees consist primarily of the audit and quarterly reviews of the consolidated financial statements and the audit of the effectiveness of internal control over financial reporting of United Airlines Holdings, Inc. and its wholly-owned subsidiaries. Audit fees also include the audit of the consolidated financial statements of United, attestation services required by statute or regulation, comfort letters, consents, assistance with and review of documents filed with the SEC, and accounting and financial reporting consultations and research work necessary to comply with generally accepted auditing standards.

Audit Related Fees. For 2019, fees for audit-related services primarily consisted of accounting consultations for proposed or future transactions and identifying and testing changes in the internal control environment prior to the implementation of the new revenue accounting system, which went into effect during the third quarter of 2019. For 2018, fees for audit-related services consisted of consultations related to the adoption of new accounting standards prior to adoption.

Tax Fees. Tax fees for 2019 and 2018 relate to professional services provided for research and consultations regarding tax accounting and tax compliance matters and review of U.S. and international tax impacts of certain transactions, exclusive of tax services rendered in connection with the audit.

All Other Fees. Fees for all other services billed in 2018 consist of subscriptions to Ernst & Young LLP's on-line accounting research tool.

PART IV