Hello Ricohoc: I too have been researching what my potential Thai tax liability is and whether I should apply for a Thai tax id number and preemptively file a Thai tax return even though I appear to have no Thai tax liability, mainly due to the fact that I do not anticipate having any remittances from overseas for at least the next 3 years. According to my research, my social security is shielded from Thai taxation by article 20 of the 1996 US-Thailand double taxation treaty. The one important step I have taken is to segregate my Social Security income from my other accounts so that there is no commingling of funds and there is a clear paper trail that the funds are social security income only. I have decided not to preemptively file a Thai tax return even though I have no tax liability, following the school of thought that by doing so, I may end up putting myself unneccessarily on the Thai Revenue Dept radar. Also, because filing a preemptive tax return would require applying for a Thai tax id number, I am hesitant to go through this process because I live in a rural area, and I suspect there aren't that many non-Thais applying for a Thai tax id number in my area, and I am apprehensive that I might run into a bureaucratic buzzsaw by applying for a tax id number, so I'm going to hold off until such time as I actually need to file a Thai tax return. My understanding is that if the only funds a US citizen remits to Thailand are social security, which are exempt from Thai taxation, there is no need to file a tax return, HOWEVER that foreign remittance of social security could trigger a Thai Revenue Dept audit, and because the burden of proof rests with you, you have to maintain a rock-solid paper trail to prove that the remitted funds are social security benefits, which is why I am setting up a separate bank account for social security benefits only. Cheers.
