A Thai tax return covers a calendar year and is due by the end of March of the following year. You file PND 91 if your only income was a salary, and PND 90 if you had several kinds of income, including foreign money you brought in. A tax ID comes from form L.P. 10.1 at any Revenue Department office, free of charge. We count your days and income, get the ID and file the return.
In short
- You are a Thai tax resident after 180 days or more in a calendar year (PwC, 24 August 2026; as of 6 October 2026). Residents pay tax on Thai income and on foreign income they bring into Thailand, non-residents only on Thai income (Revenue Department).
- PND 91 is for employment income only. PND 90 covers several types of income, including rent, business and remitted foreign income (Forvis Mazars, 31 October 2025).
- The paper deadline is the last day of March. For 2025 income the online deadline was extended by about a week. Late filing costs 1.5% a month plus a fine of up to THB 2,000.
- A tax ID is due within 60 days of your first income in Thailand, costs nothing and does not make you a resident (ThaiLawOnline, 1 October 2026).
- Foreign income earned from 1 January 2024 is taxed when remitted, in whatever year that happens. The same-year or next-year exemption is still a draft (ThaiLawOnline, 5 October 2026).
Who files, and which form?
You file if you had taxable income in the calendar year: residents on Thai income and on foreign income they remitted, non-residents on Thai income only. The form depends on the mix: PND 91 fits a salary-only year, while PND 90 covers several kinds of income, including rent, your own business or foreign money brought in.
PND 91 has a threshold: you file if employment income for the year exceeds THB 120,000 for one person, or THB 220,000 for a married couple together (Forvis Mazars, 31 October 2025). The PND 90 threshold depends on the types of income, and we check it against your papers.
You become a resident after 180 days or more in the calendar year, and days from different trips add up. A visa does not decide residency by itself. The DTV, Elite, retirement and marriage visas carry no tax relief, while some Long-Term Resident (LTR) visa categories get relief on foreign income (PwC, 24 August 2026; BOI, 6 October 2026). See DTV visa for Thailand for what that visa does and does not give you.
How do you get a Thai tax ID?
A tax ID comes from form L.P. 10.1 at any Revenue Department office, within 60 days of your first taxable income in Thailand. Bring your passport and visa, proof of a Thai address (lease, house registration or marriage certificate) and your work permit if you work. It is free and normally issued the same day (ThaiLawOnline, 1 October 2026).
The number does not make you a resident; your days do. Thai banks also ask for your home-country tax number under the CRS, which is a different number. If you are employed, you will need your work permit too: see Work permit and Non-B visa in Thailand.
Deadlines and penalties
The paper deadline is the last day of March of the following year (Revenue Department). For 2025 income the online deadline moved by about a week. Late filing costs 1.5% a month plus a fine of up to THB 2,000, and tax of THB 3,000 or more can be paid in three instalments (Forvis Mazars, 31 October 2025).
| Form | Income it covers | Deadline |
|---|---|---|
| PND 91 | Employment income only | Last day of March; online, about a week more for 2025 income |
| PND 90 | Several types: salary, rent, business, remitted foreign income | The same |
| Half-year return | Rental, professional and business income in the first half of the year | 30 September |
For 2026 income expect 31 March 2027 on paper and about a week more online, but the Revenue Department has not announced the 2027 dates. For 2025 income sources give 7 or 8 April 2026 as the online date. The half-year return applies if you had rental, professional or business income in the first six months (Revenue Department page of 21 March 2024), and we check whether yours counts.
What goes into the calculation?
A resident pays tax on foreign income when it is brought into Thailand. Income earned from 1 January 2024 is taxed on remittance in any year, while savings and earlier income are not (Por. 161/2566 and 162/2566; Brer Rabbit Legal, July 2026). Rates rise to 35%, and the first THB 150,000 is untaxed (PwC, 24 August 2026).
The untaxed band is about USD 4,500 or GBP 3,400 at illustrative rates of THB 33 and THB 44. Foreign tax is credited only where a double tax treaty allows it. Thailand has treaties with 59 jurisdictions, including the UK, the US, Australia and Germany (PwC, 24 August 2026). Thailand has exchanged data under the CRS since September 2023 and receives details of Thai residents' offshore accounts and investment income. The CRS only passes information on: tax arises when income is remitted (Forvis Mazars; Pattaya Mail, 12 January 2026).
Do not build a plan on the same-year or next-year exemption; it is still a draft (ThaiLawOnline, 5 October 2026). More in Tax on foreign income in Thailand in 2026 and Thailand's 180-day rule. A typical situation: 180 days and a savings remittance.
US citizens and other treaty residents
A US citizen stays taxable in the US on worldwide income, and the US-Thailand treaty, in force since 15 December 1997, keeps that right through a savings clause. Thai tax is then claimed as a foreign tax credit on the US return (HLB Thailand). For a UK, Australian or German resident we have not confirmed the treaty's entry-into-force date, so we read the treaty text before promising a credit. See Two tax residencies: a US citizen on a DTV.
How we prepare the return and what we need from you
We start with your days and your income: were you a resident, and what did you bring in? Then we get the tax ID, prepare PND 90 or 91, file on time and work out the treaty credit. You get a short written summary with the date the rules apply to, because the rules in this area change.
- Your passport with every entry and exit for the year, so we can count the 180 days.
- Proof of a Thai address, and your work permit if you are employed.
- Statements and certificates for salary, rent, dividends and interest.
- A record of what you brought into Thailand, with proof of where the money came from and when.
- Papers for tax paid abroad if you need a credit, and your home-country tax number.
Gather these before January, because the paper deadline falls at the end of March.
How to get started
Describe your situation in the form below: the dates you were in Thailand, your income and what you brought in. Within 24 hours we tell you whether you need to file, which form, what it costs and how long it takes. For the wider picture, see Thai taxes for foreigners.
