A federal shutdown is often described as the government running out of money. What lapses is legal authority to spend, and the consequences follow from a statute written long before modern budgeting.
Appropriations are permission, not funds
Congress passes appropriations that authorize agencies to obligate money for a period, typically a fiscal year beginning in the fall.
When that period ends without new appropriations or a stopgap measure, the authority expires. Agencies may not enter obligations they have no authority to incur.
Treasury balances are irrelevant to this. The constraint is legal permission, which is why a shutdown can occur while the government holds ample cash.
An old statute sets the rules
The Antideficiency Act prohibits federal officers from obligating funds in advance of appropriations, with penalties attached. Guidance issued decades ago interpreted it to require suspending most operations.
Exceptions cover activities necessary for the safety of human life or protection of property, plus functions funded from sources other than annual appropriations.
Each agency maintains a contingency plan identifying which positions qualify. Those plans, updated in advance, determine what actually happens on the first day.
Excepted work continues without payment
Employees in excepted roles report as normal but are not paid during the lapse, since paying them would itself require appropriations.
Others are furloughed, barred from working at all, including from checking email. Volunteering to work is prohibited rather than encouraged.
Back pay for both groups is now provided by law once appropriations resume, which resolved an uncertainty that recurred in earlier episodes.
Some functions are unaffected
Programs funded by permanent or multi-year appropriations continue, as do those financed by fees collected directly. Benefit payments authorized by standing law generally continue.
Administrative work supporting those programs may still pause, which produces the pattern where checks arrive but questions go unanswered.
The uneven map that results, with some offices open and neighboring ones closed, reflects funding structure rather than any judgment about importance.
Costs persist after resumption
Restarting suspended work involves rescheduling, backlogs and contract renegotiation. Reviews of past lapses have identified real costs from the interruption itself.
Contractors, unlike federal employees, have no statutory guarantee of recovery for lost time, and their treatment depends on individual contract terms.
Effects also reach beyond the federal payroll, since permits, inspections, loan approvals and research programs pause alongside the offices that administer them, and the delay outlasts the lapse itself.