Does the imposition of taxation inevitably erode public support for war? Through a pair of survey experiments we show that whether a war tax decreases public support for military action critically depends on the design of the taxation instrument itself. Broad-based, regressive taxes decrease support for war; progressive taxes targeted on the wealthy do not. We also uncover the mechanisms through which Americans incorporate information about war taxation into their wartime policy preferences. Economic self-interest, alone, cannot explain the individual-level variation in reactions to war taxation. Rather, Americans assess war taxation both through the lens of economic self-interest and by using partisan heuristics. The negative effect of taxation on war support is both conditional on the design of the taxation instrument and variable across segments of the public.