Economic voting theory posits that voters reward or punish incumbents based on economic performance. While institutional clarity of responsibility has been shown to condition this relationship, less attention has been paid to how perceived policy differentiation between parties shapes it. We develop a unified framework linking these two informational conditions through the concept of clarity of alternatives: the degree to which voters perceive clear, ideologically distinct policy positions between incumbents and challengers. Clarity of alternatives depends on both the separation of parties’ perceived policy stances and the precision with which those stances are understood. We, then, argue that economic voting is strongest when institutional clarity of responsibility and clarity of alternatives are jointly high, and weakest when either attribution is opaque or alternatives are ambiguous. Empirical analyses using comprehensive data from democracies worldwide support these expectations. These findings extend existing models of accountability and economic voting theory and have important implications for understanding voter behavior and party competition.