When your company in Thailand renders services for overseas clients, if the service’s end product will be used in Thailand, you need to charge VAT on your service fee. If the service’s end product will not be used in Thailand, there is no VAT involved whether or not the services are performed in Thailand.
THAI ACCOUNTANT wants to emphasize that you should consult with a knowledgeable Thai accountant before you assume the above is applicable to your business. This is because there may be more factors involved.