How much does rising federal debt raise long-term interest rates?
Core argument: The authors estimate that a 1 percentage point increase in the U.S. debt-to-GDP ratio raises long-term nominal interest rates by about 3 basis points, with term structure models indicating roughly three-quarters of that increase comes from higher term premia.
This paper revisits the relationship between federal debt and interest rates, which is a key input for assessments of fiscal sustainability. A common approach is to regress long-term forward interest rates on long-term projections of federal debt, [but the apparent disappearance of cointegration] over the last 20 years [leads us to estimate] the model in 1st differences. Our estimates indicate that a 1 percentage point increase in the debt-to-GDP ratio raises long-term nominal interest rates by about 3bps, with [the application of term structure models indicating] that about three-quarters of that increase is attributable to higher term premia. The CBO projects that the U.S. debt-to-GDP ratio will rise by 56 percentage points over the next 30 years. Holding other factors constant, our estimates suggest that the projected increase in debt would boost long-term interest rates by about 170 basis points. Given that the 5-year-ahead, 5-year Treasury rate averaged 4.35% in 2024, this would imply a rate of about 6% in 2055. Of this increase, approximately 120 basis points would stem from higher term premia, with the other 50 basis points reflecting an increase in expected short-term real rates.




