To achieve a monolithic series interconnection of tandem solar cell devices consisting of a perovskite top cell and a CIGSe bottom cell, a two-terminal interconnection scheme is introduced that includes an additional, fourth patterning step, the so-called iso-cut, which separates the window layer stack between the two solar cells. The implementation of this interconnection scheme requires a process development for a total of four structuring steps, which was achieved by systematically varying the laser parameters. Based on a detailed characterization of the individual scribe line properties with respect to their scribe line depth, morphology, electrical functionality, chemical composition and their influence on adjacent and underlying layers, the optimal patterning parameters and suitable process windows were derived for each step, which is a prerequisite for a loss-free monolithic series interconnection in a tandem module.