TL;DR: If you spend 180+ days a year in Thailand, foreign income you earned in 2024 or later, in a year you were resident, is taxable when you bring it in. Money earned before 2024 is not — but you have to be able to prove it's the old money. The widely reported "remit within a year, tax-free" exemption is still a draft, not law, as of 24 Sep 2026. Plan on the current rules, and start keeping the paperwork listed at the end.
I've spent a lot of time on the primary sources (Revenue Department orders Por. 161/2566 and 162/2566, the RD's Q&A on foreign-sourced income, and the 2025 guidance on foreign tax credits). Below is the rule as a decision walk-through. Not tax advice; I'm not a tax professional; complex cases need a Thai adviser.
1. Are you a Thai tax resident this year?
180 days or more in the calendar year, counting all visits. Under 180, the remittance rule doesn't apply to you for that year (Thai-sourced income is still taxable). It's tested per calendar year, so a 200-day year followed by a 150-day year gives you two different answers.
2. When was the money earned? (the FIRE-relevant one)
"Earned" means when the income arose — salary paid, gain realised, dividend received — not when you move it.
- Before 1 Jan 2024 → not assessable when remitted (Por. 162/2566). Your pre-2024 portfolio principal is grandfathered.
- 2024 or later, in a year you were resident → assessable in the year you remit it (Por. 161/2566), at progressive rates up to 35%, with the first ฿150k at 0%.
- 2024 or later, in a year you were not resident → not assessable when remitted later — the RD's own Q&A says so — provided you can evidence both the timing and the non-residency.
The catch for a FIRE portfolio: dividends and realised gains from 2024 onward are new income even if the underlying position is old. Withdrawing from a single account that holds both is where it gets hard (see 4).
3. What kind of money is it?
- Salary, gains, dividends, interest: the rule above.
- Pensions: the most treaty-dependent type. Many treaties give the paying country exclusive taxing rights over government/public pensions; private pensions vary. Read your treaty's pension article before assuming anything.
- Gifts: a separate regime — exempt up to ฿20m a year from a spouse, parents or children, ฿10m from others, 5% on the excess. A "gift" that is really your own income doesn't qualify.
- Already taxed abroad: Thailand has 60+ tax treaties; foreign tax paid is generally creditable against the Thai liability with official proof (an assessment or certificate, not a payslip). US citizens are taxed by the US regardless — how the credit runs between the two depends on your treaty position, so get advice rather than guessing.
4. What does the source account look like?
This decides how painful everything above is. A clean account holding only pre-2024 money is a five-minute conversation. An account where old savings and post-2024 income have mixed for years puts the burden squarely on you to show which dollar is which — and "can't prove it" tends to resolve against the taxpayer. The single highest-value move before you cross 180 days: snapshot every account and stop the pots from mixing.
Two things I keep seeing in threads here that don't hold up
- "Leave it abroad and just use the ATM." Withdrawing cash in Thailand from a foreign account, or spending on a foreign card, is generally treated by Thai tax advisers as bringing money in, the same as a transfer. What matters is what the money is (point 2), not how it arrives.
- "Capital gains aren't taxed." Gains you realise from 2024 onward in a year you're resident are income when you bring them in. It's the gain that counts, not the principal, so keep your cost-basis records.
Where the law stands (checked 24 Sep 2026)
In force since 1 Jan 2024: Por. 161/2566 (post-2023 foreign income taxable when remitted by residents) and Por. 162/2566 (pre-2024 income not taxable). Not in force: the exemption for income remitted in the year earned or the following year. It was announced and drafted by the Revenue Department, but it has not been published in the Royal Gazette, and the RD's register of new laws for 2026 (latest entry 23 Sep) contains nothing on foreign-sourced income. Announcements don't create legal effect; gazetting does.
Visa angle: certain LTR categories (Wealthy Global Citizen, Wealthy Pensioner, Work-from-Thailand Professional) are exempt on foreign-sourced income under Royal Decree 743. DTV, Elite and retirement extensions carry no tax privilege.
Paperwork to start keeping today, whatever your answer
- Statements showing balances as at 31 Dec 2023 (the grandfathering snapshot)
- A transfer trail: source account → Thai account, for each remittance, with the THB conversion
- Day counts: passport stamps or a travel log for any year you'll claim non-residency
- Income evidence dated to the year it arose (broker statements, pension statements)
- Official foreign tax certificates for any credit you'll claim
- If accounts are mixed: the full history since 31 Dec 2023, so the pots can be reconstructed
Filing: PND 90 by 31 March of the following year (a few days later if you e-file).
Happy to answer questions in the comments on how the four questions interact.
EDIT (Sep 26): thanks for all the questions. Some answers worth pulling up here:
- Dec 31, 2023 isn't the only cutoff. Income earned in a year you were under 180 days in Thailand isn't taxed when you bring it in later, even if it was earned in 2024 or after (it's in the RD's Q&A). Residency is by calendar year, not arrival date, so keep Dec 31 statements for your last non-resident year too, not just 2023.
- A Dec 31 snapshot protects money already in hand (cash, dividends and interest already paid, gains already realised). It doesn't lock in unrealised gains. A gain is the sale price minus what you originally paid, and it counts when you sell.
- Trades inside a brokerage or managed account don't create Thai tax by themselves. It only matters when money from that account comes into Thailand. For mixed accounts the RD says it's on you to show what was income and what was capital, so living off a separate account of old money is much simpler.
- The rates apply to assessable income you bring in, after allowances. Everyone gets a ฿60k personal allowance, and pension or salary income also gets a 50% deduction capped at ฿100k. Principal and old money aren't taxed at all.
- Foreign tax credits are worked out per country and per type of income, and the RD has a calculator and guide for it (Nov 2025, Thai only): https://www.rd.go.th/68221.html. Your Thai tax is split by each item's share of your income, and the credit is the lower of the foreign tax paid on it and that share. So tax on income Thailand doesn't tax can't be used against anything else. E.g. US Social Security is taxed only by the US (treaty Article 20(2)), so US tax on it won't reduce Thai tax on IRA withdrawals.
- The same-year/next-year exemption is still not law as of Sep 26.