In the United States, government shutdowns occur when funding legislation required to finance the federal government is not enacted before the next fiscal year begins. In a shutdown, the federal government curtails agency activities and services, ceases non-essential operations, furloughs non-essential workers, and retains only essential employees in departments that protect human life or property. Shutdowns can also disrupt state, territorial, and local levels of government.

In the United States Congress, an appropriations bill is legislation to appropriate federal funds to specific federal government departments, agencies and programs. The money provides funding for operations, personnel, equipment and activities. Regular appropriations bills are passed annually, with the funding they provide covering one fiscal year. The fiscal year is the accounting period of the federal government, which runs from October 1 to September 30 of the following year. Appropriations bills are under the jurisdiction of the United States House Committee on Appropriations and the United States Senate Committee on Appropriations. Both Committees have twelve matching subcommittees, each tasked with working on one of the twelve annual regular appropriations bills.