We started with a joint acct at BKK bank an absolute ‘ mare to deal with , especially for retirement visa PPWK - we moved to individual accounts at SCB and a real pleasure to work with them, got an Easi Pass account that pays 2.5% if you keep the 800k here…..
it’s not based on citizenship but residency, as is the case in most countries, if you do not intend to spend more than 6 months of the year here, you will not be tax resident so your visa requirements change accordingly
we should not underestimate the Thai RD, they have extensive systems smart people and access to all bank data. All we know for sure is that a tax resident (180 Days) is required to submit a tax return from Jan 2025, for the current tax year - of course, as with any country the requirement can be ignored, but it never goes away and back taxes, penalties and unraveling the mess can be painful - especially if you have already paid tax at home and there is a DTA. There will likely be a number of outcomes, some will leave , some will ignore and hope for the best and the rest will comply best they can, I have completed a return for last two years to claim back tax deducted at source on bank interest, and found tax dept staff extremely helpful, hopefully that will continue as tax compliance measures are stepped up.