This contribution extends the Degradation Delay Model (DDM), previously developed for CMOS inverters, to simple logic gates. A gate-level approach is followed. At a first stage, all input collisions producing degradation are studied and classified. Then, an exhaustive model is proposed, which defines a set of parameters for each particular collision. This way, a full and accurate description of the degradation effect is obtained (compared to HSPICE) at the cost of storing a rather high number of parameters. To solve that, a simplified model is also proposed maintaining similar accuracy but with a reduced number of parameters and a simplified characterization process. Finally, the complexity of both models is compared.