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How to Calculate Thai Personal Income Tax (2025)

5 min readUpdated 5 October 2026

To calculate Thai personal income tax, take your yearly income, subtract expenses (50% of salary, up to ฿100,000), subtract your allowances, then apply the progressive rates from 0% to 35% to what is left. Thai Tax Estimator does all of this for you as you type and shows whether you will get a refund or still have to pay.

It is free, needs no account and works on any phone or computer, so you can try “what if I buy more RMF?” in seconds. Your figures are calculated on your device and never sent anywhere. The tool uses the rules for 2025 income (filed in early 2026 on PND 90/91); rules change, so always confirm with the Revenue Department (กรมสรรพากร) before you file.

Do it now with Thai Tax EstimatorFree, no sign-up, works on any device.

Step by step

  1. 1Choose the income yearOpen the Thai Tax Estimator and check Income year (ปีภาษี). It starts on 2025, and the label beside it shows the year you file and the form (PND 90/91).
  2. 2Enter your incomeType your Salary 40(1) per month or per year, plus any Bonus, Fees & commissions 40(2) and Business / freelance 40(8) income. For 40(8), choose 60% deemed expenses or Actual expenses.
  3. 3Add tax already withheldEnter Tax already withheld (หัก ณ ที่จ่าย) from your 50 Tawi certificates and the Social security paid for the year (pre-filled at ฿9,000, the maximum the tool allows).
  4. 4Fill in your allowancesWork through Family, Insurance & home, Savings & funds and Donations. Each field shows its limit, and the tool caps every amount automatically.
  5. 5Read your resultSee Total tax, then Refund or Still to pay compared with what was withheld. Tax by bracket and How we got there show every number; Copy gives you a text summary.

The formula, with a worked example

Thai personal income tax follows one chain: assessable income − expenses − allowances = net income, and the progressive rates apply to net income. For salary and 40(2) income, the expense deduction is 50%, capped at ฿100,000 in total.

Example: a salary of ฿50,000 a month is ฿600,000 a year. Subtract ฿100,000 expenses, the ฿60,000 personal allowance and ฿9,000 social security, and net income is ฿431,000. Tax is 0 on the first ฿150,000, 5% on the next ฿150,000 (฿7,500) and 10% on the last ฿131,000 (฿13,100) — ฿20,600 in total, about 3.4% of income. That is exactly the example the tool opens with.

Thai income tax brackets used by the tool

The rates apply only to the slice of net income inside each band, not to the whole amount:

  • ฿0–150,000: exempt
  • ฿150,001–300,000: 5%
  • ฿300,001–500,000: 10%
  • ฿500,001–750,000: 15%
  • ฿750,001–1,000,000: 20%
  • ฿1,000,001–2,000,000: 25%
  • ฿2,000,001–5,000,000: 30%
  • Over ฿5,000,000: 35%

Tip: Moving into a higher bracket never makes your take-home pay fall — only the baht above the line are taxed at the higher rate.

Allowances the calculator includes

These are the common allowances the tool models, with the limits it applies. Temporary one-year schemes (such as Easy E-Receipt) are not included.

  • Personal ฿60,000 (always applied); spouse with no income ฿60,000.
  • Children ฿30,000 each; ฿60,000 for a second or later child born in 2018 (พ.ศ. 2561) or after.
  • Parents aged 60+ with income up to ฿30,000 a year: ฿30,000 each, up to 4. Disabled dependant: ฿60,000 each.
  • Social security up to ฿9,000. Life insurance up to ฿100,000 and health insurance up to ฿25,000, together max ฿100,000. Parents' health insurance up to ฿15,000.
  • RMF (30% of income, ฿500,000), SSF (30%, ฿200,000), provident fund (15% of salary, ฿500,000) and pension insurance (15%, ฿200,000) — all together max ฿500,000.
  • Thai ESG fund: 30% of income, up to ฿300,000, on its own limit. Home loan interest up to ฿100,000.
  • Donations: up to 10% of income after expenses and allowances; education and hospital donations count double.

Freelancers and side income

Freelance fees usually fall under 40(2), which shares the 50% / ฿100,000 expense cap with salary. Business and trading income under 40(8) can use the 60% deemed expense or your actual expenses — try both in the tool to see which leaves you better off, and keep receipts if you choose actual.

If your 40(2)–40(8) income reaches ฿1 million, a minimum tax of 0.5% of that income applies when it is higher than the bracket tax. The tool checks this and tells you when it applies. If you send invoices for freelance work, Invoice Maker handles withholding tax on the documents you issue.

Refund, PND 90 or PND 91, and the deadline

Your employer and clients withhold tax during the year and give you 50 Tawi certificates. If the total withheld is more than your final tax, you get the difference back; if it is less, you pay the rest when you file.

Salary-only earners file PND 91; anyone with other income such as 40(2) or 40(8) files PND 90. Returns for a tax year are due by the end of March of the following year, and online filing usually gets a short extension that the Revenue Department announces each year.

Tip: Planning a home purchase? Loan Calculator shows your yearly interest, which you can then enter as home loan interest here.

Questions people ask

How much salary is tax-free in Thailand?
With only the 50% expense deduction (max ฿100,000), the ฿60,000 personal allowance and ฿9,000 social security, net income stays within the ฿150,000 exempt band up to about ฿26,500 a month. More allowances raise that figure.
Is this calculator official?
No. It is an estimate to help you plan, based on the commonly published rules for 2025 income. Check the Revenue Department (rd.go.th) or a tax advisor before filing, because rules and one-off schemes change each year.
Does buying RMF or SSF really lower my tax?
Yes, within the limits. The saving is roughly your top tax rate times the amount you add. When there is room left, the tool's Room to save box shows how much more you could put in and about how much tax it would cut. Funds have holding rules, so this is not investment advice.
What is the difference between the effective and marginal rate?
The marginal rate is the rate on your last baht of net income (your top bracket). The effective rate is your total tax divided by your assessable income, which is always lower.
Do it now with Thai Tax EstimatorFree, no sign-up, works on any device.

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