Thailand Income Tax

Thailand Income Tax. Personal income tax (PIT) for individuals. This article focuses on the rules that most often trip up residents, long-stayers, and cross-border earners, with worked examples and direct references to Thai law and administrative guidance.

1) Tax residency and what Thailand taxes

Thailand taxes residents on Thai-source income and—crucially—on foreign-source income when it is brought into Thailand, subject to specific 2024-onward rules. You are a tax resident if you are present in Thailand ≥180 days in a calendar year. Non-residents are taxed only on Thai-source income. (Revenue Code s.41; Revenue Department “How do foreigners living in Thailand pay tax?”).

Since 1 January 2024, the Revenue Department’s Departmental Instruction (DI) Por.161/2566 interprets s.41(2) to tax a resident’s foreign-source income when remitted to Thailand, even if earned in earlier years. DI Por.162/2566 (20 Nov 2023) then clarified a grandfathering: foreign-source income arising before 1 Jan 2024 is not caught when later remitted. (Keep evidence of when the income arose.)

Practical takeaway: If you became resident in 2025 and remit investment income earned in 2023, that remittance is outside the DI 161 rule; income earned in 2024 or later can be taxed upon remittance.

2) What counts as “income” (Section 40 buckets)

Thai law groups “assessable income” into eight buckets under Revenue Code s.40, including: employment; hire of work; goodwill/royalties; dividends/interest/capital gains; rentals; professional fees; business income; and “other income.” Correct classification affects withholding, deductions, and the computation base. (See PwC overview reflecting these categories for individuals and treatment by type.)

3) Rates, allowances, deductions

Progressive PIT bands (2025): 0%–35% across nine tiers (THB 150,000 tax-free; 35% over THB 5m). (These brackets are stable and widely cited; verify each year.)

Common allowances & deductions (illustrative, not exhaustive):

• Standard personal allowance (taxpayer) and further allowances for spouse/children (subject to conditions).

• Social Security Fund contributions (employee) are deductible (employee rate commonly 5% of wage capped by law).

• Expense deductions vary by Section 40 income type.
  (See PwC’s “Deductions/Income determination” for current thresholds and eligibility notes.)

Investment income highlights:

• Dividends from Thai companies: WHT 10%; residents may treat WHT as final by excluding from the annual return (or include and claim credit).

• Interest: Typically WHT 15%; residents can keep it final or aggregate it.

• Capital gains: Generally taxable as ordinary income but gains on shares sold on the SET (and certain fund units) are exempt for individuals when sold on-exchange.

Note: Thailand has been discussing targeted tax relief for digital-asset gains via licensed platforms (2025–2029). Treat this as policy-in-motion until enacted; check the latest cabinet/ministerial notifications.

4) Foreign-source income and remittances: case studies

Case A — Salary from overseas remote work (2025):

• You live in Bangkok 200 days in 2025 (resident). You earn USD 120,000 from a foreign employer, paid to an offshore account. You remit THB equivalent of USD 60,000 in 2025 and keep the rest abroad. Thailand taxes the portion remitted in 2025 as foreign-source income under DI 161. If foreign tax was paid, claim foreign tax credit under the relevant DTA, supported by official proof.

Case B — Investment portfolio built before moving:

• You worked abroad 2015-2023, accumulated dividends and gains. You become Thai resident in 2025 and bring that pre-2024 nest egg into Thailand in 2025. DI 162’s grandfathering means no Thai PIT on remitting amounts arising before 1 Jan 2024. Keep dated statements to evidence when income arose.

Case C — 2024 dividends remitted in 2026:

• You earned foreign dividends in 2024 while resident and remit them in 2026. The remittance year (2026) triggers Thai tax on that 2024-arising income due to DI 161’s interpretation. Consider whether WHT abroad is creditable under the DTA.

Possible rule easing (proposal): There has been a proposal to exempt foreign-source income if remitted within the year of earning or the following year; remittances after that window would be taxable. As of 1 Sep 2025, treat this as proposed (not law) and monitor formal adoption.

5) Employment income, fringe benefits, and social security

Employment income for services performed in Thailand is Thai-source, taxable regardless of payment location (e.g., paid offshore). Housing benefits, tax paid by employer, and other perquisites are generally taxable unless a specific exemption applies. Employees typically contribute to the Social Security Fund; employer contributions do not reduce the employee’s taxable income, but the employee’s own contributions are deductible up to the statutory ceiling. (Confirm current contribution caps and any temporary reliefs each year.)

6) Investment and passive income—Thai specifics

• SET shares: Individuals enjoy capital-gains exemption when selling on-exchange; dividends carry 10% WHT (optionally final). If you include dividends in your return, you may gross up/claim credit per rules.

• Bank interest: WHT 15%; small savings interest may enjoy limited exemption thresholds.

• BOI dividends: Dividends paid from BOI-promoted profits can be tax-exempt (documentation matters).

7) Special regimes: LTR visa (selected categories)

Holders of the Long-Term Resident (LTR) Visa in the Highly Skilled Professional track may be eligible for a 17% flat PIT on income from qualifying employment in targeted industries (distinct from ordinary progressive rates). Carefully verify your LTR category, employer/industry qualification, and Board of Investment (BOI) certification.

8) Filing, withholding, and deadlines

The Thai tax year is calendar-year. Employers withhold PIT monthly on Thai employment income. Individuals file PND 90/91 returns after year-end; the paper filing deadline is typically 31 March, with e-filing usually extended into early April (exact cut-off is announced annually). If you exclude dividend/interest under final WHT, do not re-include those amounts in your computation. (Check the Revenue Department’s seasonal notices each year.)

9) Worked computation (resident with mixed income)

• Facts (2025): Employment THB 2,400,000 (Thai-source); SET share sale gain THB 300,000 (on-exchange); Thai dividends THB 100,000 (WHT 10%); foreign dividends THB 200,000 (earned 2024, remitted 2025); Social Security (employee) THB 9,000 (illustrative cap).

• Treatment:

  • Employment: fully taxable.

  • SET gain: exempt.

  • Thai dividends: elect final 10%; exclude from return.

  • Foreign dividends (2024-arising, remitted 2025): taxable in 2025 under DI 161 (no grandfathering because income arose after 1 Jan 2024). Consider foreign tax credit.

  • Deduct allowable expenses/allowances and Social Security, then apply bands to net taxable income.10) Audit-ready documentation checklist

• Residence days log (entry/exit stamps, TM30/TM6 history).

• Source evidence for foreign income: contract notes, dividend advices, bank statements showing date earned vs date remitted (critical for DI 162 grandfathering).

• WHT certificates (Thai and foreign) to support final treatment or foreign tax credit.

• Proof of BOI/LTR eligibility if claiming special rates