Eddy Current Testing (ECT) is a standard technique in industry for the detection of surface breaking flaws in ferromagnetic materials such as steels. In this context, simulation tools can be used to improve the understanding of experimental signals, optimize the design of sensors or evaluate the performance of ECT procedures. CEA has developed for many years semi-analytical models embedded into the simulation platform CIVA [1] dedicated to non-destructive testing. Following a previous work carried out at the laboratory in the case of one flaw located in a cylindrical ferromagnetic part, the developments presented herein address the case of a flaw located inside a planar and ferromagnetic medium. The theoretical approach will be presented, as well as comparisons between simulation data obtained from the literature.