The U.S. spends $1 trillion a year to service its debt. Here's why experts say that's a concern.

The Republicans' "big beautiful" budget package is uniting everyone from Elon Musk to Wall Street over an issue that experts say could pose a threat to the nation's long-term fiscal stability: The rising cost of servicing the U.S. government's growing mountain of debt. 

The U.S. spent $1.1 trillion in interest on its debt in 2024 — almost double the amount it was paying five years ago, according to Federal Reserve Bank of St. Louis data. The nation now spends more on interest payments than it does on defense, data from the Stockholm International Peace Research Institute shows.

Those costs could rise even more under the Republican tax and spending bill now being considered in the Senate, according to a June 5 analysis by the Congressional Budget Office. The version of the tax bill passed by the House last month is projected to increase the federal deficit — the gap between what the federal government spends each year and what it collects in revenue — by $2.4 trillion over the next decade, the nonpartisan agency found.