Of course this is Thailand and up to now, and maybe forever, they will say mai pen rai no need to file if you actually owe no tax. They can do anything they want. And as I said, they are quite reasonable so why make anybody file if they do not owe? Somewhere in their tax code you will actually see a provision that says rd “will” waive any payment of 5 baht or less. I just saw it but cannot find it again to post. So, remember this is Thailand, which is actually a GREAT place.