Usually you have to do for all ratings the check , that you can write in your new license , this is the same as license conversion, ICAO to EASA and vice versa . When you convert license it must be valid (license must be valid and rating (SEP ,MEP ,IR etc... at time of check for new license in order to transfer rating in to the new license) . Example in case of CPL with MEP IR - Pass 13 exams ATPL Theory, CPL check flight, when license is at your hands, then IR ,Type Rating etc...