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You become a Thai tax resident for a year when you spend 180 days or more in Thailand between 1 January and 31 December, in one stretch or several, and your nationality does not matter. 179 days do not make you a resident, and 180 do. In a resident year, foreign income you earn from 2024 on is taxed when you remit it to Thailand, and you file a PND 90 or 91 return by 31 March of the following year. Rules are as of 6 October 2026.
In short
- A resident spends 180 days or more in Thailand between 1 January and 31 December, in one stretch or several, whatever the nationality (Revenue Department Q&A, January 2024; PwC, 24 August 2026).
- Each calendar year is counted on its own: 250 days in a row (100 at the end of one year and 150 at the start of the next) make you a resident in neither.
- A resident pays tax on Thai income and on foreign income remitted to Thailand. A non-resident pays only on Thai income (Revenue Department Q&A, January 2024; infographic, 2024).
- A tax ID (TIN) does not make you a resident, and neither does a visa: the Destination Thailand Visa (DTV) and the Elite, retirement and marriage visas give no relief.
- The return for the year is due by 31 March, with e-filing for 2025 running about a week longer. Late filing brings a surcharge of 1.5% a month, and a fine of up to THB 2,000 is possible (Forvis Mazars, 31 October 2025).
How are the 180 days counted?
Days are counted from 1 January to 31 December, in one stretch or several, whatever your nationality. Revenue Department examples: 366 and 184 days make a resident, 179 do not, and 250 days in a row (100 at the end of one year and 150 at the start of the next) make a resident in neither year (Revenue Department Q&A, January 2024).
| Days | A resident that year? |
|---|---|
| 366 days, the whole year | Yes |
| 184 days over several trips | Yes |
| 179 days | No |
| 250 days in a row: 100 at the end of one year and 150 at the start of the next | No, in neither year |
| 65 days | No, and that year's foreign income is not taxed on remittance |
The Revenue Department materials we read do not say how to count the day of arrival and the day of departure. If you are close to the line, count both and keep your tickets, boarding passes and passport stamps, because a dispute will turn on them. Here is how it looks on a calendar (both days counted, dates illustrative).
| Situation | Days in the calendar year | A resident? |
|---|---|---|
| A winter stay from 1 November to 31 March, no other trips | 61 in the first year and 90 in the second | No, in neither year |
| A southern-hemisphere winter escape, 1 June to 30 September | 122 | No |
| Arrive 1 July, leave 31 December | 184 | Yes |
| Arrive 15 July, leave 31 December | 170 | No |
| Two trips of 100 days in one year | 200 | Yes |
| One DTV entry of 180 days within a year | 180 | Yes |
What changes when you become a resident?
A resident pays tax on Thai-source income and on foreign income brought into Thailand; a non-resident pays only on Thai-source income. Foreign income is taxed if you earned it from 1 January 2024 in a resident year and remit it in the same or a later year (Revenue Department infographic, 2024).
| Non-resident | Resident | |
|---|---|---|
| Income from Thai sources | Taxed | Taxed |
| Foreign income | Not taxed, even if remitted | Taxed on remittance if earned from 1 January 2024 in a resident year |
| Tax paid abroad | Not applicable | Credited under a treaty, up to the Thai tax |
Thailand foreign income tax in 2026: what is taxed after 180 days explains how remittance works, what is exempt and which documents you need. If you spent fewer than 180 days in a year, that year's foreign income stays outside the tax when remitted, and so do savings built up while you lived abroad (Revenue Department Q&A, January 2024).
How do the tax ID and the PND 90 or 91 return work?
A tax ID (TIN) is for anyone with assessable income: you apply within 60 days of the first income, on form L.P. 10.1 at any Revenue office. There is no fee, and the number is normally issued the same day. A TIN does not make you a resident, because the 180-day test decides that (ThaiLawOnline, 1 October 2026).
You need your passport, a current visa, proof of a Thai address (a lease, house registration or a marriage certificate) and a work permit if you are employed. Banks now also ask for your home-country tax number under the Common Reporting Standard (CRS); it is not the Thai number.
The return covers a calendar year and includes your Thai-source income for the year plus foreign income remitted during it (Revenue Department infographic, 2024). File PND 91 if your only income is employment, and PND 90 if you have several kinds, including remitted foreign income. For 2025 income the paper deadline was 31 March 2026 and e-filing ran about a week longer: Forvis Mazars says 7 April 2026, other sources 8 April. Tax of THB 3,000 or more can be paid in three instalments, on 31 March, 30 April and 31 May. Late filing brings a surcharge of 1.5% a month, and a fine of up to THB 2,000 is possible (Forvis Mazars, 31 October 2025).
For 2026 income, expect 31 March 2027 on paper and about a week later online, but the Revenue Department has not announced the 2027 dates.
Gather four groups of documents before you file:
- statements for foreign accounts as at 31 December 2023, if you remit savings, and records that separate capital from profit;
- the bank document for every transfer into Thailand during the year;
- proof of your days: tickets, boarding passes, passport stamps;
- certificates of tax paid abroad, if you claim a credit, in English or Thai (ThaiLawOnline, 5 October 2026; Revenue Department infographic, 2024).
Do visas change the count?
No. The visa does not affect residency, because days are counted. The Destination Thailand Visa (DTV), Elite, retirement and marriage visas give no tax relief. The DTV allows up to 180 days per entry, so one entry that falls entirely within a calendar year already reaches the line (ThaiLawOnline, September 2026).
More on the DTV is in DTV visa in 2026: requirements, documents and where to apply after 31 August.
The Long-Term Resident (LTR) visa offers tax relief: foreign income is exempt in the Wealthy Global Citizen, Wealthy Pensioner and Work-from-Thailand categories, and highly skilled professionals pay a flat 17% on Thai employment income (BOI, 6 October 2026).
What if two countries treat you as a resident?
Thailand and your home country can both treat you as a resident. Then you consult the double tax treaty between the two countries: Thailand has such treaties with 59 jurisdictions, including the UK, the US and Australia (PwC, 24 August 2026). Which residency tie-breaker articles those treaties contain is not confirmed in our sources, so we read the treaty text for your case.
Your days in Thailand settle only the Thai side. A US citizen stays taxable in the US on worldwide income whatever the count, and claims a credit for Thai tax: the US-Thailand treaty has been in force since 15 December 1997 and has a savings clause (HLB Thailand, 4 October 2020). The UK and Australia apply their own residency tests, so a person can be a resident of both countries in the same year. For how this plays out for an American on a DTV, see the typical situation Two tax residencies: a US citizen on a DTV.
What next
Describe your situation in the form on the taxes page, and a lawyer replies within 24 hours. We count your days by year, help with the tax ID and file PND 90 or 91 on time. See how this works on Filing a Thai tax return as a foreigner.
For what is taxed after 180 days, read Thailand foreign income tax in 2026, and for how it plays out in practice see the typical situation 180 days and a savings remittance: what was taxed and what was not.
Rules checked as of 6 October 2026.
