What is the US national debt made of?

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

Once a month Treasury publishes the Monthly Statement of the Public Debt (MSPD). It is the most detailed official account of what the US owes: every kind of security, how much of each, and, in its longer tables, every single issue and when it matures. This guide reads the statement for 31 August 2026.

The total, and its two halves

On 31 August 2026 total public debt outstanding was $40.18 trillion. The statement splits it two ways.

By who holds it:

Debt held by the public is owed to anyone outside the federal government, including the Federal Reserve and foreign governments. Intragovernmental holdings are owed by Treasury to other parts of the government, mostly trust funds such as Social Security's.

By kind of debt:

Marketable debt is what Treasury sells at auction and anyone can trade. Nonmarketable debt cannot be traded. Most of it, $8.11 trillion, is Government Account Series securities held by the trust funds; the rest includes savings bonds ($146.9 billion) and State and Local Government Series securities ($78.9 billion).

Marketable debt by security

Table 1 breaks marketable debt into the securities sold at auction. The shares are our arithmetic from the published amounts.

(A small amount, $3.6 billion, is held by the Federal Financing Bank, so the shares add to just under 100%.) Notes are the largest part. Bills, at less than a quarter of the total, are the part that turns over fastest: every bill matures within a year, so the whole stock is repaid and sold again every few months. The guide to bills, notes, bonds, TIPS and FRNs explains each kind.

The other tables

• Table 2 gives the statutory debt limit and the debt subject to it, as of the month-end.
• Table 3 lists every marketable security still outstanding, with its issue date, maturity date, rate and amount. 500metrics adds up Table 3 by month of maturity for the Treasury maturities page, which is why that page is dated by month-end.

Monthly statement or daily figures?

The statement is a month-end snapshot, published a few business days after the month closes. The statement for 30 September 2026 is due on 6 October 2026. For a daily total, Treasury publishes Debt to the Penny: on 30 September 2026 it was $40.17 trillion. The statement goes into much more detail; Debt to the Penny is out sooner. For the debt limit, the Daily Treasury Statement is the measure the debt limit page uses. The same statement reports Treasury's cash, which the guide to the Treasury General Account explains.

What this guide cannot tell you

• Who outside the government holds the debt, by country or by type of investor. The statement does not say. Treasury publishes foreign holdings separately, and 500metrics does not cover them at launch.
• What the debt will be next month. 500metrics shows each statement as published and does not project it.