This paper shows how the design of fiscal policy and the characteristics of government debt can drive significant differences in monetary transmission within and across countries with different fiscal contexts, and across models with different fiscal specifications. Using a tractable HANK model, I derive analytical expressions for the effects of fiscal policy on monetary transmission as the sum of three channels: a debt service channel, a debt composition channel, and a fiscal cyclicality channel. The magnitudes and directions of these channels are strongly context dependent, being determined by the interactions between the size and composition of government debt, the choice of fiscal rule, the progres-sivity of the marginal fiscal instrument, and the distribution of government debt ownership. For a given fiscal block used in a theoretical model, or for a given fiscal context observed in the data, the framework explains when the fiscal channels are large or small, and why they amplify or dampen monetary policy.