The Treasury maturity wall, explained

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

The maturity wall is the amount of US Treasury debt that comes due over a stretch of time, usually the next 12 months. It is large every year, because a large part of marketable debt is in bills that last a year or less. Treasury repays maturing securities mostly by selling new ones, so the wall is a measure of how much must be borrowed again, at whatever rates apply at the time.

How the amount is counted

At the end of each month, Treasury's Monthly Statement of the Public Debt lists every marketable security outstanding, with its maturity date and amount. It is published on the fourth business day of the next month. At 31 August 2026 it listed 463 securities, with 68 different maturity dates in the following 12 months.

500metrics adds up the amount maturing in each calendar month. Three choices change the total, and each page states them:

• Marketable debt only. Securities owned by federal trust funds are not traded and are left out.
• Gross of the Federal Reserve. The total includes the Treasury securities the Federal Reserve owns. That share is shown separately, because it is refinanced differently: what the Fed reinvests arrives at auction as a SOMA add-on rather than from other bidders.
• Whether TIPS and floating rate notes are in. TIPS principal moves with inflation, so their amount at maturity is not known in advance.

A practical trap: when a security has been reopened, the statement carries its whole outstanding amount on one row. Counting every row would count it more than once.

Why so much matures

Treasury issues bills every week, and every bill matures within a year. On top of that sit notes and bonds issued years ago that are now close to maturity. A larger share of debt in bills makes the wall taller even if total debt does not change. The weighted average maturity of marketable debt sums this up: the shorter it is, the more of the debt is repriced each year.

Rollover is routine

Rollover is the normal way Treasury handles maturing debt: the cash from new auctions settling on the same day pays off the old securities. The 13-week bill alone offered $95 billion at its auction of 28 September 2026, and it is one of several bill terms auctioned every week. The debt that is rolled over is replaced at the yields of the new auctions.

That is where the wall meets interest cost. At 31 August 2026 the average interest rate on marketable Treasury debt was 3.475%. Debt that matures and is replaced at a higher auction yield raises the interest bill; debt replaced at a lower yield lowers it. 500metrics plans a separate refinancing scenario, labelled as a scenario, not a prediction.

Month-end snapshots

The wall changes every month as bills mature and new securities are issued. 500metrics keeps a permanent copy of each month-end, for example the maturity snapshot of 31 August 2026, so a reporter can cite the figure as it stood on a date. The full list is at History.

What these numbers cannot tell you

• How much Treasury will borrow in total. New borrowing also covers the deficit, and cash balances move.
• The interest rate on the new debt. It is set auction by auction.
• Anything about corporate, mortgage or property debt that also "matures" in a given year. These pages cover US Treasury marketable debt only.