The US debt limit, explained

Drafted with AI assistance from official sources; checked against the sources listed below.

The debt limit is the most the US Treasury is allowed by law to owe at one time. It covers nearly all federal debt, both the debt held by investors and the debt the government owes its own trust funds. When borrowing reaches the limit, Treasury cannot add to the total until Congress raises or suspends it.

How much room is left, and how it is measured

The room left under the limit, sometimes called headroom, is the limit minus the debt subject to the limit. Treasury reports both every business day in Table III-C of the Daily Treasury Statement.

Example: 30 September 2026 (amounts from Table III-C, in millions of dollars):

Source: U.S. Treasury, Daily Treasury Statement, Table III-C, for 30 September 2026, checked 2 October 2026. The totals are our arithmetic from the published rows.

So on that day the government owed about $40.17 trillion, of which $39.98 trillion counted toward the limit, leaving about $1.12 trillion of room.

Debt subject to the limit is not total debt

The two differ by a little under $200 billion. The gap is mostly the unamortized discount on securities sold below face value, such as bills, which counts toward the limit only as it accrues. Some public figures subtract total debt from the limit and so understate the room. Every 500metrics figure names which of the two it uses.

Does the debt limit expire?

No. A limit stays in force until Congress changes it. What expires is a suspension. When Congress suspends the limit, Treasury may borrow without a cap until a set date; the day after, the limit comes back at the amount of debt then outstanding.

The last cycle shows both: the limit was suspended from June 2023 to 1 January 2025 (Table III-C shows the limit as 0 for those days), came back on 2 January 2025 at about $36.1 trillion, and was raised by $5 trillion on 4 July 2025 to $41.104 trillion, where it stands. Each year's daily history is on its year page, for example the debt limit in 2025.

Extraordinary measures

When debt subject to the limit reaches the limit, Treasury can keep paying for a while with extraordinary measures: legal accounting steps that reduce the debt counted against the limit. The best known is pausing new investments of federal employee retirement funds, such as the Thrift Savings Plan's G Fund, which are made whole once the limit is lifted. Treasury also stops selling State and Local Government Series securities.

While the measures are in use, debt subject to the limit sits at or just under the limit, so the room left reads near zero. How much the measures have left is not in Table III-C. Treasury reports it in its own statements during a debt-limit period, and 500metrics links those reports when they appear.

Treasury's cash

The Treasury General Account is Treasury's cash account at the Federal Reserve. On 30 September 2026 it closed at $984,046 million. Cash and room left are different things: room left is how much more Treasury may borrow; cash is what it has on hand to pay with. When the limit binds, the cash balance and the measures together set how long payments can continue. The debt limit page shows both for the same day. The guide to the Treasury General Account explains why the balance swings.

What an X-date is

The X-date is the first day Treasury would be unable to pay all of the government's obligations in full and on time, once the measures and the cash run out. It is always a projection. The Congressional Budget Office, the Bipartisan Policy Center and others publish estimates, and they move with tax receipts and spending. 500metrics shows each published estimate with its publisher and date and never makes one of its own.

What these numbers cannot tell you

• When cash runs out. The room left is room to borrow, not a countdown.
• How much the extraordinary measures have left, which Table III-C does not report.
• What Congress will do. The limit changes only by law, and the pages report changes after they happen.