In this thesis, a-posteriori error estimates for time discretizations of the incompressible time dependent Stokes equations by pressure-correction methods are presented. Pressure-correction methods are splitting schemes, which decouple the velocity and the pressure. As a result the Stokes equations reduce to much easier schemes, which can be solved by cost-efficient algorithm. In a first step, a-posteriori estimates for the instationary Stokes system, discretized by the two-step backward differential formula method (BDF2), are presented. This allows to compare the a-posteriori estimators of the discretized Stokes system with the estimators of the pressure-correction scheme. In the second part of the thesis rigorous proofs of global upper bounds for the incremental pressure correction scheme discretized by backward Euler scheme as well as for the two-step backward differential formula method (BDF2) in rotational form are presented. Moreover, rate optimality of the estimators are shown for velocity (in case of backward Euler and BDF2 in rotational form) and pressure (in case of Euler). Computational experiments confirm the theoretical results.