The effects of different undercoats and silicon nitride nucleating layers on the coercive force, anisotropy field, and 5 to 100 MHz complex permeability spectra of magnetically soft, Ni81Fe19 multilayer thin films sputtered onto flexible, 52-μm-thick polyethylene terephthalate substrate for use as identification markers or electromagnetic interference shields is reported. In comparison to films deposited directly onto the substrate, nonmagnetic undercoat layers, including aluminum, copper, silicon, and silicon nitride, are found to increase the soft magnetic properties of subsequently deposited films. Nucleating layer effects are dependent upon the undercoat/nucleating layer combination.