With Singapore, I believe you need to satisfy certain criteria to make sure your business qualifies as offshore, other than simply selling a service offshore and not in Singapore itself. Additional factors such as revenue not being remitted to Singapore, Directors being outside of Singapore, keeping the bank account elsewhere should definitely preclude you from being classified as onshore for tax purposes. I believe that even if you do have a bank account in Singapore, you should be able to be classified as offshore. Best to talk to a local lawyer with experience in Offshore Companies.