The US Federal Fiscal Year
October 1 to September 30: history, naming convention, and what FY versus CY means in federal contracting.
October 1 start date
The US federal fiscal year runs October 1 through September 30. The convention was set by the Congressional Budget and Impoundment Control Act of 1974 and took effect with FY1977. Before 1977, the federal fiscal year ran July 1 through June 30, the convention in force since 1842.
The shift to October was intended to give Congress more time to enact appropriations bills before the new fiscal year began. In practice, continuing resolutions are now routine, but the October 1 boundary remains in force.
Naming convention
A US federal fiscal year is labelled by the calendar year in which it ends. FY2025 starts October 1, 2024 and ends September 30, 2025. Federal contractors and grant recipients should always confirm whether a contract or solicitation references FY (October–September) or CY (calendar year, January–December) — they differ by nine months for the same year label.
Government shutdowns
When appropriations are not enacted by October 1, federal agencies that depend on annual appropriations enter a shutdown until either appropriations or a continuing resolution is enacted. Shutdowns affect calendar planning for federal contractors because period-of-performance clauses are typically dated to the fiscal year, not the calendar year.
Naming convention and contracting
Federal fiscal years are labelled by the year they end. FY2025 starts October 1, 2024 and ends September 30, 2025. Federal contracts cite the fiscal year in which obligations are funded; a contract awarded in August 2025 is FY2025 funding; a contract awarded in October 2025 is FY2026 funding. Period-of-performance dates, deliverable schedules, and close-out reports all anchor on these boundaries.
The September 30 fiscal cliff produces a predictable annual surge in federal contract awards, especially in the final two weeks of FM12. "Use it or lose it" is a real planning constraint: most federal appropriations are one-year money and lapse on September 30 unless re-obligated.
Continuing resolutions and the budget calendar
When Congress fails to enact appropriations bills by October 1, federal agencies operate under a continuing resolution (CR) that typically funds programmes at the prior-year rate. CRs introduce planning uncertainty: agencies cannot start new programmes, sign multi-year contracts, or move money between accounts. The longer the CR, the more compressed the actual obligation window once full-year appropriations are enacted.
If you contract with the federal government, build CR scenarios into your forecast. A 90-day CR moves your effective FY1 obligation from FM1 to FM4; a year-long CR effectively rebases your business on the prior-year budget regardless of what the new appropriations bill said.