Electromagnetic interference (EMI) filters are essential for attenuating high frequency noise and ensuring compliance with electromagnetic compatibility (EMC) standards in power electronic systems. However, traditional discrete EMI filters often face significant volumetric constraints due to the separate placement of magnetic components and capacitors, which limits the suitability for the compact modern devices. To address this limitation, planar magnetic integration technology has been employed to consolidate inductors and capacitors onto multilayer substrates, thereby significantly reducing the overall physical volume. However, under high-frequency operating conditions, parasitic elements intrinsic to integrated circuit structures, such as interwinding capacitance, leakage inductance and dielectric substrate losses, significantly alter the impedance profile of filter components and compromise the noise attenuation capabilities. In this paper, a high frequency parasitic model for planar integrated T-type CM EMI filters is developed to precisely characterize the impedance behavior and quantify the effect of parasitic elements on insertion loss performance. An equivalent circuit representation of the integrated filter components is derived, then a simulation framework employing coupled impedance analysis is established to evaluate insertion loss characteristics of the planar T-type configuration, this provides a theoretical basis for the design and optimization of electromagnetic integrated common-mode filters.