Who needs a TIN (and who doesn't)
The TIN (Tax Identification Number) is your Thai tax number: 13 digits that identify you to the Revenue Department, the same way your tax number identifies you back home. You need it when you have income to declare in Thailand, and for an expat that comes through two doors: a Thai salary or business, or being a tax resident under the 180-day rule and bringing foreign income into the country. What counts as "bringing" has its own fine print — it's explained in the guide to what counts as remitted money.
The reverse reading holds too: if you live there half the year but that year you have no Thai income and remit nothing, there's no taxable income to declare. In practice, many expats get the TIN before they need it anyway, because the bank asks for it on its tax residency forms and because having it ready in January saves you a scramble. The legal theory, by the way, says you apply within 60 days of your first taxable income.
How to apply: office, papers and timing
You apply for the TIN at the Revenue Office for your district — the office that matches the address where you live, not some headquarters in Bangkok. The document kit is short:
- Passport with your valid visa.
- Proof of address: your lease, or the residence certificate immigration issues.
- The registration form (L.P. 10.1), which they hand you and help you fill in right there.
The process is free and quick: many offices hand over the number the same day, and the rest within two or three working days. Go in the morning, bring photocopies of everything, and write down your exact address in Thai if you have it — it's the piece of information they'll ask for most.
The Thai tax calendar
The Thai tax year is the calendar year: January to December. And the return is filed in the first quarter of the following year. The full scheme:
| Date | What happens |
|---|---|
| Jan 1 – Dec 31 | Tax year: the calendar year's income accrues |
| During the year | TIN registration: in theory, within 60 days of your first income |
| January 1 | The window opens to file for the previous year (PND 90/91) |
| March 31 | Deadline if you file on paper, at the office |
| April 8 | Deadline with e-filing in 2026: filing online buys a few extra days |
Translated: what you remit to Thailand in 2026 is declared between January and March 2027. You always have a quarter's margin on the closed year.
PND 90 or PND 91: which one is yours
The Thai return comes in two forms, and choosing is easy:
- PND 91 — only for those whose sole income is a salary from an employer. The case of the expat hired by a Thai company.
- PND 90 — for everything else: multiple sources, freelance income, rentals… and remitted foreign income. If you live on what you bring in from abroad, this is your form.
And from what amount is filing mandatory? The bar is low: for a single person, ฿120,000 a year if you only have salary income and ฿60,000 if you have other income (for married couples filing jointly, ฿220,000 and ฿120,000). Mind the nuance: crossing the minimum obliges you to file, even if you owe nothing — the first ฿150,000 being taxed at 0% doesn't spare you the paperwork.
Filing it: online or in person
There are two roads, and both work:
- E-filing: the Revenue Department's online portal (efiling.rd.go.th). You register with your TIN and file from home, with the bonus of the extra deadline days. The catch: the site is mostly in Thai, so the first time is usually done with someone beside you who can read it.
- In person: at your Revenue Office, where the staff help you fill in the form. The Revenue Department publishes English versions of the forms and their guides, which are handy for showing up with your numbers already prepared.
Whichever road you take, the material is the same: your TIN, the summary of what you've remitted or earned in the year, withholding certificates if you've had an employer, and receipts for the allowances you plan to claim.
The basic allowances
Before the brackets apply, the base is trimmed by the allowances. The ones almost everyone uses:
- Personal: ฿60,000 — automatic, just for existing.
- Spouse with no income: ฿60,000 more.
- Per child: ฿30,000 — plus an extra ฿30,000 for the second and subsequent children born from 2018.
- Expenses against salary: 50%, capped at ฿100,000, no receipts needed.
There are more (insurance, pension funds, donations), but the basics alone show the picture: a single employee stacks ฿100,000 in expenses, ฿60,000 of personal allowance and the 0% bracket — their first ~฿310,000 of the year pays nothing. The full brackets, from 0 to 35%, are in the taxes in Thailand guide.
What happens if you don't file
The Thai stick for being late is small if it stays an oversight, and serious if there's intent:
- Filing late: a fine of up to ฿2,000.
- Tax left unpaid: a surcharge of 1.5% per month until it's settled.
- Deliberate concealment: another league — the law provides for up to ฿200,000 and up to a year in prison.
And the context that changes everything: Thailand now takes part in the automatic exchange of bank information (CRS). Your accounts abroad are not invisible.
Frequently asked questions
Do I need a TIN if I don't bring money into Thailand?
The TIN is for when there's income to declare: a Thai salary or remitted money while you're a tax resident. With neither, there's no taxable income that year. Even so, many get it before they need it because the bank asks for it on its tax residency forms.
When is the return filed?
Between January 1 and March 31, covering the previous calendar year. E-filing buys a few extra days: in 2026, until April 8.
Do I have to file even if I owe zero?
Yes, if you're over the minimum: ฿120,000 a year of salary or ฿60,000 of other income for a single person. The 0% bracket makes many returns come out at zero, but the obligation to file doesn't go away.
What if I file late?
A fine of up to ฿2,000 for the delay and, if you left tax unpaid, a surcharge of 1.5% per month until it's settled.