Within a joint collaboration, a ±525 kV HVDC GIS cable connection assembly has now been fully qualified for the first time with a type test and a pre-qualification test according to CIGRE TB 852. The interface design of this gas-insulated cable connection assembly is based upon the dimensions used in the HVAC GIS standard IEC 62271-209. Using this standard will reduce risk during implementation due to the well-known scope split. The paper describes the cable connection assembly interface, the testing philosophies and the performed tests. All tests were performed successfully.