EMI filters design is a rather difficult task. This is particularly true for common mode and differential mode inductors. Indeed, engineers have to choose adequate materials, design the magnetic circuit, and choose the number of turns. The final design must achieve the attenuation requirements (constraints) and has to be as compact as possible (goal). AC analysis is a powerful tool to predict global impedance or attenuation of any filter. However, AC analysis are generally performed without taking into account the frequency-dependent complex permeability behaviour of soft magnetic materials. That’s why, in this paper, we developped two complex permeability frequency dependent models. Both models are build thanks to the references [1], [2] and [3]. Simulated (from one model only) and measured (on a Fe-based nanocrystalline material) real and imaginary parts of the complex permeability are shown in Fig 1. Once the model fully implemented, 4 different simulations of a complete EMI filter were carried out (see Fig.2): case “a” : Inductors and capacitors are ideal case “b” : Inductors are ideal and capacitors are not (replaced by serial RLC model) case “c” : Inductors are replaced by one of our model, capacitors are as in case 2 case “d” : Windings parasitic capacitances are added to the EMI filter model It can be seen in Fig.2, that including the frequency-dependent complex permeability model in the EMI filter simulation improved significantly the accuracy (case “c” versus “a” and “b”) between 20 kHz and 1 MHz. It is specifically in this range that the permeabilty is changing a lot (see Fig.1). After 1 MHz, it is necessary to add a parasitic capacitor to the model to be more realistic (case “c” versus “d” and measurement). The extended paper will explain in detail the both models of frequency-dependent complex permeability and how to implement them in LTSpice software. Results of both models will be compared and discussed (some new cases of simulation may be added).