As such, the monthly borrowing for 2026 now sits at roughly $155 billion, or $39 billion per week. And, like any borrower, that debt carries an interest cost. The latest monthly budget review from the Congressional Budget Office (CBO) confirms that net interest on public debt for the fiscal year has hit $857 billion: roughly $23.8 billion a week.

This is approximately $100 billion more (13%) than the interest paid out in the first nine months of 2025, the CBO adds, owing to a higher total debt burden than last year and higher long-term interest rates.

In fact, interest payments on the debt are now $20 billion larger than the outlays for the Departments of Defense, Commerce, Homeland Security, Education, the Environmental Protection Agency, the Small Business Administration, and the U.S. Coronavirus Refundable Credits scheme—combined.

Also contributing to the demand on government purse strings is the increasing demand for social security, Medicare and Medicaid.

Spending for Social Security benefits rose by $62 billion (or 5%) because of increases in average benefits and in the number of beneficiaries, CBO noted. In comparison, Medicare outlays increased by $58 billion (8%) due to higher enrollment and higher payment rates for services. Rising costs per enrollee meant Medicaid spending increased by $49 billion (10%).

This is a trend that isn’t going anywhere: The U.S. population is aging. According to the Census Bureau, Americans’ median age—the age at which half of the population is younger, and half is older — continues to rise, climbing from 39.2 in 2024 to 39.4 in 2025.

Men’s share of the older population is particularly of note, the bureau adds. In 2001, there were 70.6 males for every 100 females age 65 and older, but by 2025, the ratio had increased substantially to 81.6.

Debt trajectory

With the factors influencing Treasury spending only embedding further over the coming decades, those concerned about the U.S. fiscal trajectory are calling for action.

So far, they haven’t got much response—though there is a growing sense of urgency among policymakers, according to experts.

The latest CBO estimates have alarmed the likes of the Committee for a Responsible Federal Budget which, for a long time, has been lobbying the government to address its borrowing.

In a statement shared with Fortune, Maya MacGuineas, president of the committee, said: “The FY 2026 deficit has now passed the FY 2025 deficit–and it is likely to stay that way for the rest of the fiscal year … We will likely borrow $2 trillion or more this fiscal year—an astounding figure given that the economy keeps growing and unemployment is low.”

The current situation is “likely the tip of the iceberg,” MacGuineas adds, if policymakers don’t make changes to entitlements and “ignore the need to cut spending and increase revenues,” she adds: “Social Security and Medicare are within seven years of trust fund exhaustion, and action needs to be taken to prevent across-the-board cuts to both programs.”

MacGuineas advocated targeting a deficit of 3% of GDP, roughly half its current level, a proposal that has gained support across the political spectrum. But she also added that “more importantly,” politicians should be “honest with the public about the grave dangers we face by remaining on this unsustainable path.”