Abstract. The U.S. national debt exceeded $1 trillion, driven by COVID-19 spending and military conflicts. Debt service payments rose 80.4% in four years, from $521 billion to $940 billion. This paper presents a macroeconomic model analyzing the monetary policy’s impact on debt service and national debt growth. Federal spending is divided into real expenditures on goods/services and interest-sensitive debt payments. The model suggests that if the interest sensitivity of debt payments surpasses that of household/business spending, expansionary monetary policy results in a negative macroeconomic multiplier, posing significant challenges for policymakers amidst growing debt service obligations.

Keywords: government debt service, deficits and debt, fiscal policy, monetary policy, IS-LM, interest rates, real GDP.