In countries with large informal labor markets, pension eligibility rules can shape workers' employment decisions. We study this relationship in Brazil using a life-cycle model that captures the interaction between contributory pensions and labor market informality. The model highlights how minimum contribution requirements affect the trade-off between higher short-term earnings in informal employment and future pension benefits from formal work. Counterfactual simulations show heterogeneous effects of stricter eligibility rules. Low-income workers reduce formal participation and rely more on the social pension, middle-income workers increase formality to qualify for benefits, while high-income workers remain formal throughout their working lives.