The Fair-Value Accounting and Budget Act amends the Congressional Budget and Impoundment Control Act of 1974 to mandate the use of fair-value credit estimates for federal loan and loan guarantee programs. This legislation requires the Congressional Budget Office (CBO) to provide these fair-value estimates for any measure establishing or modifying such programs, and to include them in its annual "The Budget and Economic Outlook" report. These CBO estimates are crucial, as the chairs of the House and Senate Budget Committees must use them for budget enforcement purposes. Furthermore, the bill requires the Director of the Office of Management and Budget (OMB) to submit an annual report to Congress, starting in 2026, detailing fair-value estimates of federal credit program costs. Both the CBO and OMB are specifically directed to use the definition of "fair-value" as set forth by the Government Accounting Standards Board's 2015 publication.