A government shutdown occurs when Congress fails to pass appropriations legislation before the current funding expires and the President signs a continuing resolution or full-year spending bill to restore it. During a shutdown, federal agencies that rely on annual appropriations must cease non-essential operations; employees in those agencies are furloughed — sent home without pay, though they typically receive back pay once the shutdown ends.
Shutdowns are always the result of a breakdown in the appropriations process. They're not accidents — they happen when Congress can't reach agreement on funding legislation, or when the President refuses to sign what Congress passes.
What the Antideficiency Act Requires
The legal basis for shutdowns is the Antideficiency Act (31 U.S.C. 1341), which prohibits federal agencies from obligating or spending money that Congress hasn't appropriated. When appropriations lapse at midnight on September 30 (the end of the federal fiscal year, or at the expiration of a continuing resolution), most agencies must immediately stop spending. Agency general counsel offices issue "shutdown plans" well in advance of anticipated lapses, detailing which functions are funded through other means and which must stop.
What Shuts Down
Agencies funded through annual discretionary appropriations shut down. This includes: the Department of Transportation, the Department of Housing and Urban Development, parts of the Department of Justice, the IRS during filing seasons (with significant disruption), the FDA, parts of the Department of Agriculture, national parks and monuments, federal museums, and agencies that issue permits or process applications requiring appropriated staff time.
What specifically stops within each agency depends on the agency's shutdown plan. Typically: public-facing services that require appropriated staff cease; government websites may go dark or stop updating; permit applications and inspections stop processing; and federal employees are told not to report to work or check email.
What Stays Open
Not everything funded by the federal government requires annual appropriations, and not everything that does stops completely during a shutdown.
Mandatory programs continue. Social Security, Medicare, Medicaid, SNAP (food stamps), and other entitlement programs operate under permanent appropriations — they don't require annual funding bills to continue. Benefit checks keep going out during shutdowns.
Military personnel work — but may not get paid on time. Active-duty military personnel are required to report for duty during a shutdown as a matter of law (they're "excepted" from furlough requirements). Their pay, however, depends on whether the Treasury has appropriated funds to cut checks on the normal schedule. In past shutdowns, military pay has sometimes been delayed by days.
Essential services continue. Air traffic control, border protection, law enforcement, emergency medical response at VA facilities, and other functions deemed "essential" operate during shutdowns. Employees performing these functions are required to work without immediate pay, receiving back pay when appropriations are restored.
Programs with multi-year appropriations continue. Some programs receive appropriations that cover multiple years. If those funds haven't been exhausted, the program can continue operating during a shutdown.
How Long Shutdowns Last
The duration varies enormously. The longest shutdown in U.S. history ran 35 days, from December 22, 2018 to January 25, 2019, stemming from a dispute over border wall funding. Shorter shutdowns have lasted hours or a weekend. Most resolve within days because the political pressure — on both parties, from constituent complaints and economic disruption — becomes too large to sustain.
Shutdowns end when Congress passes and the President signs a continuing resolution or an appropriations bill. Typically, back pay is authorized in the same legislation. Federal employees who were furloughed receive retroactive pay for the shutdown period; federal contractors, by contrast, generally do not receive compensation for work time lost during a shutdown.
The Appropriations Deadline and Fiscal Year
The federal fiscal year runs October 1 through September 30. Congress is supposed to pass all twelve annual appropriations bills before October 1. In practice, this almost never happens. The typical pattern is one or more continuing resolutions — temporary funding at prior-year levels — while negotiations continue, followed eventually by either full-year appropriations or an omnibus bill combining multiple subcommittee bills.
When a continuing resolution expires and no replacement has been passed, a shutdown begins. LegislationPatch tracks all appropriations legislation; when a CR or funding bill is moving through the process, it appears in our database with its current legislative stage.