500 hours...
I had this conversation with the CAA recently. If you operate a single pilot certified aircraft multi pilot, you must have multi pilot SOPs in place. The time counts towards your 500 hours. So, if you do 500 hours on a B200 you have satisfied part of the requirements to unfreeze your ATPL. However, you need to pass a ATPL Skill Test, which is your LST on your first MPA. FCL didn't state any difference between private or AOC. I currently fly a B200 on a private operation, the operator and insurance company insist on a multi pilot operation so why shouldn't the hours count.....