Emerging economies that have adopted inflation targeting and that combine low credibility, high public debt, and a high interest rate suffer from a typical problem. Increases in the interest rate to reduce departures of inflation from the target imply that a higher primary surplus is required for stabilizing public debt/GDP ratio. This tricky situation is known as “unpleasant fiscal arithmetic” (UFA). This article develops a theoretical model showing how increased financial openness and capital account liberalization can mitigate UFA. Furthermore, empirical evidence from the Brazilian case through OLS, GMM, and GMM system methods is offered. The findings show that increases in capital mobility and financial openness work as a commitment technology, which contributes to the success of the inflation targeting and thus reduces the risk of UFA.