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A typical situation assembled from practice; details are changed.
A British client spent his first year over 180 days in Thailand and brought money in from the UK. Crossing 180 days made him a Thai tax resident for that year, so he needed his first Thai tax return, the PND 90 form. It included the UK rental income he remitted during the year; savings held since before 2024 did not need to go on it. Before filing, we got him a Thai tax ID.
The situation
Our client retired to Phuket in early 2025 on an annual retirement extension of stay and spent around 195 days in Thailand that year, counting all his trips. During the year he transferred about £25,000 to Thailand to live on: roughly £15,000 from savings held in a UK account since before 2024, and about £10,000 from rent on a house he still owns in the UK, earned in 2025. He has no Thai-sourced income, and he assumed a return was only for people who work in Thailand.
Why a return was needed
A person becomes a Thai tax resident once their stay reaches 180 days or more in a calendar year (Revenue Code, s. 41); days from separate trips add up, and the visa type makes no difference. We start with the calendar-year day count, because everything else follows from it. Our client passed 180 days in 2025, so he was a resident for that year. The rule is set out in more detail in the 180-day rule.
Since 1 January 2024, a resident who remits foreign income into Thailand pays tax on it, under Revenue Department instruction Por. 161/2566: remitted foreign income earned from 2024 onward is taxable when brought in, and money saved earlier needs paperwork to prove it. A proposed exemption for income remitted the same or following year has not become law, so the question reaches retirees and remote workers too, not only employees. Thailand has also exchanged account data under the CRS since September 2023; the exchange itself creates no tax.
Which income went on it and which did not
To work out what belongs on a PND 90, our lawyers sorted the client's money by year and checked what could prove each date: when was it earned, and was it remitted to Thailand. Here is how his money broke down.
| Money (illustrative) | Earned | Remitted in 2025 | On the PND 90 |
|---|---|---|---|
| UK savings, about £15,000 | Before 2024 | Yes | Not included; dated bank statements on file |
| UK rental income, about £10,000 | 2025 | Yes | Included |
| Remaining 2025 rent | 2025 | No, kept in the UK | Not included |
The rent left in his UK account is not on this year's return, because it was not remitted; if he brings it in during a later resident year, it goes on that year's return instead. Tax on remitted foreign income covers the rule in more detail.
Pension income follows the same rule
A pension, dividend or interest payment sorts the same way as rent: by when it was earned and whether it was remitted, not by its label. Whether a tax treaty gives relief for tax already paid at home, or exempts some income in Thailand, is a separate question that we check against the treaty text.
PND 91 is only for income entirely from employment; his rent made PND 90 the right form.
Getting a tax ID and filing
- We counted his 2025 days from passport stamps and flight records.
- We collected dated statements for the savings account and the account that received the rent.
- We got him a Thai tax ID (TIN), 13 digits, on form L.P. 10.1 at a Revenue office, with his passport, visa and a lease agreement as proof of address; no fee, and the number is usually issued the same day.
- We completed the PND 90 with the remitted rent on it and the savings left off.
- We filed before 31 March 2026, the paper deadline for 2025 income, rather than wait on the e-filing extension.
- We explained that tax of THB 3,000 or more can be paid in three instalments.
The result
The 2025 PND 90 return was filed on time, with the remitted rent on it and the savings, backed by statements, left off. The tax was worked out from the client's own figures; in another case, the outcome depends on the paperwork and the tax office. He now keeps his own log of days and transfers; we expect the paper deadline for 2026 income to fall on 31 March 2027, though the Revenue Department has not announced that date yet.
If your situation is similar
A first return goes smoothly once you count your calendar-year days early and sort remitted money by the year it was earned, with entry and exit dates, dated statements and proof of your Thai address ready before the deadline. If savings and income sit in the same account, 180 days and a savings remittance shows how another client separated them before remitting.
If this is your first year past 180 days and you have brought money in, send us your travel dates and statements. We will tell you whether a return is due, what belongs on it, and the cost before we start, and we answer within 24 hours by Telegram, WhatsApp or the form on this site. Our approach is on the page filing a Thai tax return.
