Output voltage is an important performance characteristic of planar insulating core transformer (PICT). In PICT magnetic cores are insulated from their neighboring magnetic cores by solid insulating materials. Solid insulating materials can increase leakage flux. This results in a low generated voltage in secondary coils, especially on the upper stages. Connecting flux compensation capacitors to secondary coils can compensate the flux loss. Design equations to calculate the flux compensation capacitors value and relevant simulation by CST and Protel software were presented. Simulation results of an actual PICT showed that output voltage increased by 19% after being connected to flux compensation capacitors and the voltage on every stage was equally distributed. Results of simulation were consistent with the following experimental test, which revealed that flux compensation capacitors were effective.