Why it matters: An upward shift in long-term interest rates is putting the government on track to spend much more on interest payments in the coming years than was anticipated just a few months ago.

• If current rates stay high and fiscal policy matches current forecasts, the cost of servicing those debts will surpass defense spending in 2025 and top Medicare spending in 2026.

• In the current fiscal year, interest spending is on track to surpass $800 billion, more than double 2021's $352 billion figure. In 2026, the government's net interest expense would reach 3.3% of GDP, the highest on record.

• Those numbers are from the Committee for a Responsible Federal Budget, on the assumption that rates remain 1 percentage point higher than in the Congressional Budget Office's forecasts, based on the CBO's rules of thumb.

By the numbers: In July, the CBO fiscal projections assumed that the 10-year U.S. treasury bond would yield 3.8%, which was about where the securities were trading at the time.