¿From a theoretical viewpoint, political budget cycles (PBC) arise in equilibrium when rational voters are imperfectly informed about the incumbent's competency and the incumbent enjoys discretionary power over the budget. This paper focuses on the second condition, specifically examining how PBC in the composition of government spending are affected by separation of powers. With an exogenous status quo, the details of the budgetary process, namely, the status quo location, the agenda-setting authority and the degree of compliance with the budgetary law, play critical roles for the existence and the size of PBC. With an endogenous status quo given by the previous period's budget, PBC only arise when there is low compliance with the budgetary law. What drives these results are effective checks and balances, that provide a commitment device to solve the credibility problem behind PBC.JEL Classification: D72, D78.