The United States is facing a growing budget problem that stems not just from new spending, but from the heavy burden of interest payments on trillions of dollars already borrowed. As the national debt continues to climb, these interest costs are becoming one of the biggest factors pushing deficits higher in the years ahead.
This week, the U.S. passed a troubling milestone. As of March 31, 2026, debt held by the public reached $31.27 trillion, slightly larger than the nation’s annual economic output. This pushed the debt-to-GDP ratio above 100 percent for the first time in recent memory. While lawmakers in the future could add more borrowing, much of the projected increase in deficits will come from paying interest on past debts.
Federal budget deficits are already running above $2 trillion this fiscal year. Interest payments alone are heading toward $1 trillion annually. According to the Congressional Budget Office (CBO), interest costs could rise to $2.1 trillion by 2036. At that point, publicly held debt is expected to equal about 120 percent of GDP.
Analysts at Deutsche Bank have noted that the U.S. is entering a period of “fiscal dominance,” where the huge debt load limits the Federal Reserve’s options. Raising interest rates too aggressively to fight inflation could trigger a fiscal or financial crisis. This situation may also lead to higher inflation over the long term.
The CBO projects that the primary deficit — the gap between government revenue and spending, not counting interest payments — will stay relatively steady at around 2 percent of GDP. This holds even as costs for Social Security and Medicare increase due to more baby boomers retiring. However, when interest payments are added in, the total deficit is expected to grow from about 6 percent of GDP today to nearly 10 percent by the mid-2050s.
For many years, the difference between primary and total deficits was small. That changed after the COVID-19 pandemic, when massive government spending increased the debt and high inflation led the Fed to raise rates sharply. The CBO’s forecasts assume that interest rates and economic growth will remain fairly stable. If those assumptions prove wrong, the debt situation could become even more challenging.
Rising defense needs are adding pressure. The recent war against Iran has used up large supplies of advanced munitions, requiring expensive restocking. The Trump administration wants to increase the Pentagon’s budget to about $1.5 trillion per year to modernize the military and produce more weapons. Some officials, including White House budget chief Russell Vought, have expressed concern that such large increases could worsen the deficit.
Historian Niall Ferguson has warned that any great power spending more on debt interest than on defense risks losing its strength. Interest payments started exceeding defense spending in 2024, meeting what some call “Ferguson’s Law.” Boosting military budgets could temporarily reverse this, but interest costs are still projected to top $2 trillion in the next decade even without extra defense spending.
The CBO’s long-term outlook may actually be somewhat optimistic. In some years during the 2030s, borrowing costs are expected to grow faster than the economy itself. With debt already larger than the economy, future presidents and Congresses may find their choices limited not just by new priorities, but by the need to manage the enormous pile of existing debt.
As interest payments consume more of the federal budget, they will crowd out other priorities and make it harder to address long-term challenges without difficult choices on spending, taxes, or both. The sheer size of past borrowing is now shaping America’s fiscal future.
