This paper examines how the maturity structure of sovereign debt shapes fiscal–monetary inter actions in the United States. Using exogenous monetary policy shocks and nonlinear local projections, we show that debt maturity influences both the fiscal consequences of monetary tightening and its macroeco nomic transmission. When the government relies more heavily on short-term debt, contractionary monetary policy shocks lead to large and persistent increases in public debt, more pronounced deteriorations in fiscal and financial conditions, and significantly larger declines in output, inflation, and private investment. These ef fects are substantially attenuated when debt maturity is longer. […]