There are so many variables to this that it's incomprehensible as to how it would work. In 15 yrs of making Thailand my main place with 5 yrs here full time I've never met one foreigner who filed taxes. The subject has never come up. Why is that?
I've been chastised and ridiculed for stating it's a ploy to drum up business for so called Tax experts.
Besides our US 1040 form the folks here will need to deal with dozens of other countries and their tax forms.
Now, I can understand tax refugees, foreigners with huge amounts of money invested in Thailand, Thais who work overseas. These people should be the first to be scrutinized. But, to suggest the run of the mill retiree here is going to be hauled in for not paying tax is absurdly ludicrous.