The number: $40 trillion
$40.047tn
US gross federal debt passed $40 trillion for the first time on 18 August 2026.
Source: US Treasury, Debt to the Penny
Why it’s news
It came early. According to MercoPress, the Congressional Budget Office had projected $39.4 trillion by the end of the 2026 financial year, and didn’t expect the $40 trillion line to be crossed until 2027.
Why it matters
The US funds that debt by selling Treasury bonds, and the more it sells, the more investors can demand to hold them. In August the 30-year Treasury yield touched 5.323%, its highest in 19 years. The 10-year finished last week at about 4.9%.
Why it matters here: US government borrowing costs influence borrowing costs around the world, including UK government bonds, which feed into the price of fixed-rate mortgages.
What it doesn’t mean
A big number on its own isn’t a crisis. What matters is whether investors keep buying the bonds, and at what price. That’s why the Treasury’s buybacks, and its borrowing plans on Wednesday 4 November, are worth watching. We explain the buybacks here.
Still checking
“US interest costs now exceed defence spending.”
Checking
Status: checking. You’ll see it everywhere this year. Reports disagree on how it’s measured, so we’re checking the Treasury’s full-year figures before giving a verdict. It’s logged on our claim checks record.
Finformed is independent research. Not financial advice. Spotted an error? Email [email protected] and we’ll correct it at the top of this piece, with the date.
Sources
- US Treasury, Debt to the Penny (daily data). fiscaldata.treasury.gov
- MercoPress, US gross national debt passes 40 trillion dollars for the first time, 21 Aug 2026. en.mercopress.com
- Yahoo Finance, Treasury doubles long-term bond buybacks to $4 billion, 19 Aug 2026 (30-year yield high). finance.yahoo.com
- Yahoo Finance (Stocktwits), Weekly Spread, 31 Oct 2026 (10-year close). finance.yahoo.com
