Every year Congress must pass twelve appropriations bills to fund the discretionary side of the government by October 1, the start of the federal fiscal year. It rarely finishes on time, so it usually passes continuing resolutions that extend current funding for weeks or months. When neither happens, money for the affected agencies runs out, and the government shuts down in whole or in part.
This guide explains why shutdowns happen, who controls the outcome, which services stop and which keep going, and how shutdowns end. Each agency and process links to a full entry.
A shutdown ends when Congress passes, and the President signs, a continuing resolution or full-year appropriations, sometimes bundled into an omnibus bill. The legislation that ended the 2025 shutdown funded most agencies through January 30, 2026, passed three full-year spending bills, guaranteed back pay, and reversed layoffs issued during the shutdown. Proposals to prevent shutdowns, such as automatic continuing resolutions, have been introduced repeatedly but not enacted.
There have been about twenty funding gaps since the modern budget process began in 1976, but only a handful of long, full shutdowns. The longest were 21 days in 1995 to 1996 over spending cuts, 16 days in 2013 over the Affordable Care Act, 35 days in 2018 to 2019 over border wall funding, and 43 days from October 1 to November 12, 2025, over health insurance subsidies and spending levels. In 2026 a brief lapse followed from January 31 to February 3, and a dispute over immigration enforcement left the Department of Homeland Security unfunded from February 14 to April 30. Supporters of using deadlines as leverage say they force action on priorities, while critics say shutdowns waste money and harm workers and the public without changing outcomes.
Funding bills move through the House and Senate appropriations committees and need majorities in both chambers and the President's signature. In the Senate, most spending bills need 60 votes to overcome a filibuster, which gives the minority party leverage. Congressional leaders negotiate the deals, and the Office of Management and Budget directs agencies on how to shut down, including which employees are excepted from furlough.
About a quarter of federal spending is discretionary, set each year in twelve appropriations bills. The rest, including Social Security, Medicare, and interest on the debt, is mandatory and flows under permanent law. When the fiscal year begins without an appropriation for an agency, the Antideficiency Act forbids it to spend or obligate money, with narrow exceptions. Until 1980, agencies often kept operating through funding gaps, but opinions by Attorney General Benjamin Civiletti in 1980 and 1981 concluded that the law requires them to stop.
Each agency follows a contingency plan approved in advance. Typically, national parks close or operate without staff, museums close, research grants and new contracts stop, small business loans and many permits are delayed, and routine inspections and data releases are suspended. Delays pile up, and some lost work, such as missed scientific seasons or postponed court dates, cannot be made up later.
Benefits funded by permanent law, including Social Security, Medicare, and veterans' benefits, continue, though some customer services slow. Agencies funded by fees or their own revenue, such as the Postal Service and the Federal Reserve, are not affected. Programs with leftover or multiyear money can run for a time, which is why food assistance and the courts can keep going for a few weeks before funds run low. In November 2025, food assistance benefits under SNAP were delayed and only partly paid after court fights over contingency funds.
For the people caught in the middle, see who gets furloughed in a shutdown. For the bigger picture, read how the federal budget works, or compare shutdowns with a different kind of fiscal deadline in the debt ceiling explained.