US National Debt Tops $40 Trillion As Borrowing Costs Hit Households

U.S. national debt has moved above $40 trillion for the first time, putting renewed attention on federal deficits just as rising Treasury yields are making mortgages, car loans and business borrowing more expensive.

The milestone was recorded in August and has returned to the center of the market debate this week as a global bond selloff pushes U.S. government borrowing costs higher. The 10-year Treasury yield rose to about 4.79% on Tuesday, up sharply from roughly 4.20% at the beginning of 2026, according to market figures reported by The Associated Press.

What the $40 trillion figure includes

The national debt is the accumulated total of annual federal deficits. It includes debt held by investors, banks, pension funds, foreign governments and the Federal Reserve, as well as securities held by federal trust funds and other government accounts.

It is different from the annual budget deficit, which measures how much more the government spends than it collects during a single year. The Congressional Budget Office projects a $1.9 trillion deficit for fiscal 2026, equal to 5.8% of gross domestic product. That is well above the 3.8% average recorded over the past 50 years.

Debt held by the public, the measure economists often use when assessing the fiscal burden, is projected to equal 101% of GDP this year and rise to 120% by 2036 under current law, according to the CBO.

Why higher debt can affect household finances

Americans do not receive a personal bill for the national debt. Its effects can nevertheless reach household budgets through financial markets and future policy choices.

The Treasury must regularly sell bonds to finance deficits and refinance maturing obligations. If investors demand higher yields to hold that debt, those rates can influence borrowing costs throughout the economy. Mortgage rates tend to track the 10-year Treasury yield, while credit conditions for businesses, consumers and local governments also respond to changes in benchmark government rates.

Higher federal interest expenses can create another pressure point. The CBO estimates that net interest outlays will reach about $1 trillion in 2026, or 3.3% of GDP. That would exceed federal spending on every mandatory program except Social Security and Medicare.

The compounding cost of interest

Interest costs rise for two reasons: the government owes more money, and older debt is gradually refinanced at newer interest rates. When the Treasury borrows to cover those interest payments, it adds to the stock of debt and can make later costs grow faster.

The CBO projects net interest expenses will more than double to $2.1 trillion by 2036. In that projection, interest would consume 4.6% of GDP and nearly match all federal discretionary spending.

Those forecasts are not guarantees. Faster economic growth, lower rates, higher revenue or spending restraint could improve the path. Recessions, military conflicts, tax reductions without offsetting savings or persistently high interest rates could worsen it.

What Washington could eventually face

Reducing debt growth usually requires some combination of lower spending, higher taxes and faster economic expansion. Each option involves political and economic trade-offs. Abrupt spending cuts or tax increases can weaken demand, while delaying action can make the eventual adjustment larger.

Debt concerns can also restrict the government’s ability to respond to a future recession or emergency. If interest payments claim a growing share of revenue, lawmakers have less room to finance new priorities without borrowing even more.

What to watch next

• the direction of 10-year and 30-year Treasury yields;
• monthly federal deficit and interest-cost figures;
• Congressional decisions on taxes and spending;
• and whether economic growth keeps pace with the debt.

The debt total alone does not predict an immediate fiscal crisis. The United States borrows in its own currency and Treasury securities remain central to global finance. The speed of debt growth and the rising cost of servicing it, however, are becoming more important to investors, policymakers and households.

Sources: Associated Press report on the $40 trillion milestone; Associated Press explanation of rising bond yields; Congressional Budget Office 2026–2036 outlook.

This article is for general information and does not constitute investment advice.