Every Thai company, every foreign company doing business in Thailand, and many foreign companies that only receive Thai-sourced income pay corporate income tax (CIT) under the Revenue Code. The system is simple on paper: a flat 20% rate on net profit. The detail that costs founders money is elsewhere: the SME rate conditions, the half-year prepayment, non-deductible expenses, and the 10% that applies again when profits leave the country.
1. Who pays and on what#
| Taxpayer | Taxed on |
|---|---|
| Thai company or partnership (juristic person) | Worldwide net profit |
| Foreign company carrying on business in Thailand (branch, or via an agent or employee) | Net profit from Thai business |
| Foreign company not carrying on business in Thailand | Gross Thai-sourced income, by withholding: 15% on most items (interest, royalties, service fees), 10% on dividends |
| Foreign company transporting passengers or goods | Gross receipts at special rates (3% for international transport) |
A partnership registered at the DBD (limited or registered ordinary partnership) is a juristic person and pays CIT. An unregistered ordinary partnership is taxed under personal income tax.
Foreign income of a Thai company. The 2024 remittance rules for individuals do not apply to companies. A Thai company pays CIT on its worldwide net profit under sections 65 and 66 of the Revenue Code. It makes no difference whether the money ever reaches Thailand. Invoicing an overseas client, or collecting payment into a foreign bank account held for the company, does not move that income out of Thai CIT. Where the same profit is taxed abroad, Thailand's double taxation agreements can reduce withholding or give a foreign tax credit. To use them, you usually need a Certificate of Residence from the RD.
2. Rates#
Standard rate#
20% of net profit.
SME rates#
A company qualifies if its paid-up capital is no more than 5 million THB at the end of each accounting period and its revenue from sales of goods and services is no more than 30 million THB a year.
| Net profit (THB) | Rate |
|---|---|
| 0 – 300,000 | 0% |
| 300,001 – 3,000,000 | 15% |
| Over 3,000,000 | 20% |
Planning point. Paid-up capital above 5 million THB loses the SME rates permanently for that year. Immigration's 2 million THB per foreigner guideline means a company with three foreign work permits (6 million THB) cannot be an SME. Weigh the tax cost against the visa benefit before you increase capital.
Other rates#
- BOI-promoted activities: exemption or 50% reduction for the promoted period.
- International Business Centres (IBC): reduced rates of 8%, 5% or 3%, tied to annual Thai spending.
- Branch profit remittance: an extra 10% on amounts remitted abroad (see section 7).
3. Filing calendar#
| Return | What | Deadline |
|---|---|---|
| PND.51 | Half-year return. Prepay half of the estimated full-year tax, based on estimated annual profit. Listed companies and banks use actual six-month results. | Within 2 months after the end of the first 6 months |
| PND.50 | Annual return with audited financial statements | Within 150 days after the fiscal year-end |
| e-Filing | Through efiling.rd.go.th | An extra 8 days for both returns, under the RD's e-filing extension, which currently runs for returns due up to 31 January 2027 (RD e-tax measures; check whether it is renewed after that) |
For a 31 December year-end:
- PND.51 is due by 31 August (8 September if e-filed);
- PND.50 is due by 30 May (around 7 June if e-filed).
The PND.51 trap. If your half-year estimate is more than 25% below the actual annual tax without reasonable cause, the RD adds a surcharge of 20% of the shortfall. Estimate conservatively high if the business is growing fast.
4. Net profit: what is and is not deductible#
Net profit is accounting profit adjusted by the Revenue Code (Section 65 bis and 65 ter).
Common adjustments#
| Item | Tax treatment |
|---|---|
| Entertainment | Deductible up to 0.3% of gross receipts, capped at 10 million THB, with supporting documents |
| Donations to public charities | Up to 2% of net profit |
| Donations to education or sport via approved programmes | Additional deductions under specific decrees |
| R&D | 200% deduction for qualifying R&D with approved institutions or registered projects |
| Training of employees | 200% for qualifying training expenses |
| Depreciation | Maximum rates by asset class: buildings 5%, machinery 20%, computer hardware/software 33.33% (3 years) |
| Passenger cars | Depreciation on cost capped at 1 million THB per car; rental capped at 36,000 THB/month |
| Provisions (bad debt, warranty) | Not deductible until the conditions for write-off are met |
| Fines, surcharges, CIT itself | Not deductible |
| Expenses without a proper tax invoice or receipt | Often disallowed |
| Personal expenses of directors or shareholders | Not deductible |
| Salary of the owner-director | Deductible if reasonable and with PND.1 withholding |
Losses#
Tax losses can be carried forward for 5 accounting periods. There is no carry-back.
5. Worked example: a Bangkok SME#
Bangkok Design Co., Ltd. has paid-up capital of 2,000,000 THB and revenue of 18,000,000 THB. Its accounting profit is 1,950,000 THB.
| Adjustment | THB |
|---|---|
| Accounting profit | 1,950,000 |
| + Entertainment over limit (spent 120,000; limit 0.3% × 18M = 54,000) | +66,000 |
| + Traffic fines | +4,000 |
| + Personal travel of a director booked to the company | +80,000 |
| − Extra 100% deduction for qualifying staff training (spent 100,000) | −100,000 |
| Net taxable profit | 2,000,000 |
Tax at SME rates:
- first 300,000 at 0% = 0;
- next 1,700,000 at 15% = 255,000 THB.
Tax at the standard 20% would be 400,000 THB, so SME status is worth 145,000 THB this year.
Prepayment. If the company estimated 1,800,000 THB of profit in its PND.51, it prepaid half the tax on that estimate. The estimate of 1,800,000 is 10% below the final figure, so there is no surcharge. Tax on 1,800,000 at SME rates is 0 + 1,500,000 × 15% = 225,000, and half of that, 112,500 THB, was paid with the PND.51. The balance of 142,500 THB is paid with the PND.50.
Withholding tax deducted by clients (3% on services) is also credited against the final CIT. Many service SMEs end up with a refund position.
6. Withholding tax credits and refunds#
Thai customers that are companies withhold 3% on service fees and issue a 50 Tawi certificate. These certificates are credited in the PND.50. Keep every original; missing certificates are the most common reason for losing credits. Refunds are possible but often trigger a tax audit, so many SMEs instead carry the credit forward to offset future tax.
7. Getting profit out: dividends and remittances#
| Payment | Tax |
|---|---|
| Dividend from a Thai company to a foreign company | 10% withholding, reducible under some double tax agreements |
| Dividend to a Thai company | Exempt if the recipient holds 25%+ for 3 months before and 3 months after (unlisted), or other holding conditions are met |
| Dividend to an individual | 10% withholding; Thai residents may elect it as final or claim a dividend tax credit |
| Branch profit remittance abroad | 10% of the amount remitted, filed on PND.54 within 7 days of the remittance |
| Interest or royalties to a foreign company | 15%, reducible under DTAs |
Dividend timing. A Thai company can pay dividends only from retained profits approved at a shareholders' meeting. Interim dividends can be paid by board resolution, and must be reported at the next meeting. At least 5% of each dividend must go to a legal reserve until the reserve reaches 10% of capital (Civil and Commercial Code s.1202).
8. Transfer pricing#
- Companies with revenue of 200 million THB or more that have related-party transactions must file the transfer pricing disclosure form with their PND.50.
- The RD may also ask for a TP local file.
- Even small companies must price intra-group services and loans at arm's length.
- An interest-free loan from a Thai company to its parent or director can attract deemed interest.
Global minimum tax (Pillar Two)#
This only affects subsidiaries of large groups. The Emergency Decree on Top-up Tax B.E. 2567 applies to fiscal years starting on or after 1 January 2025. It covers Thai entities that belong to a multinational group with consolidated revenue of at least EUR 750 million in two of the four preceding years. When the group's effective tax rate in Thailand falls below 15%, a top-up tax brings it up to 15%. A BOI exemption can push the rate below 15%. Thailand has adopted all three mechanisms: the domestic minimum top-up tax (QDMTT), the income inclusion rule (IIR) and the undertaxed profits rule (UTPR). The top-up return and the GloBE information return are generally due 15 months after year-end, or 18 months for the first year. A standalone SME is not in scope.
9. Penalties#
| Failure | Consequence |
|---|---|
| Late filing | A fine of up to 2,000 THB, plus surcharge |
| Late payment | Surcharge of 1.5% per month on the unpaid tax, capped at the tax amount |
| Under-reporting found on audit | Penalty of up to 100% of the tax shortfall (reduced on voluntary disclosure), plus surcharge |
| PND.51 underestimation by more than 25% | Surcharge of 20% of the shortfall |
10. Annual CIT checklist#
- [ ] Month 1–2 after half-year: PND.51 estimate and payment.
- [ ] Year-end: confirm SME status (capital at year-end; revenue for the year).
- [ ] Collect all 50 Tawi certificates from customers.
- [ ] Audit completed and approved by the AGM within 4 months of year-end.
- [ ] PND.50 filed within 150 days, plus 8 days if e-filed.
- [ ] Audited financial statements filed at DBD within 1 month of the AGM.
- [ ] Transfer pricing disclosure form, if revenue is 200M THB or more.
- [ ] Dividend: legal reserve set aside; 10% withheld; PND.54 for foreign shareholders.
Frequently asked questions#
Does a dormant company still file PND.50? Yes. Every registered company files a PND.50 and audited financial statements every year, even with no revenue.
Is there a minimum tax? No. A loss-making company pays no CIT, but still files.
Can I change the accounting year? Yes, with Director-General approval.
What exchange rate do I use for foreign-currency income? The Bank of Thailand rate, under the rules in the Revenue Code. Your accountant applies the year-end revaluation rules.
Does a startup with BOI promotion still file PND.51 and PND.50? Yes. It reports promoted income as exempt and pays tax on any non-promoted income.
When are SME rates lost? If paid-up capital exceeds 5 million THB at the end of the accounting period, or revenue exceeds 30 million THB.
Compare Bangkok accounting and tax firms in our directory.
Related guides#
- VAT Registration in Thailand: The 1.8M THB Threshold, PP.30 Filing and Tax Invoices
- Withholding Tax in Thailand: Rates, PND Forms and Deadlines for Businesses
- Accounting and Audit Requirements for Thai Companies
- BOI Promotion in Thailand: Incentives, Eligibility and How to Apply
Sources
- Revenue Department, Corporate Income Tax (English): https://www.rd.go.th/english/6044.html
- Revenue Code, Chapter 3 Part 4 (Sections 65–76 bis)
- Royal Decree No. 530 and successive decrees on SME rates
- Revenue Department e-Filing: https://efiling.rd.go.th
- Emergency Decree on Top-up Tax B.E. 2567 (Royal Gazette, 26 December 2024)
- PwC Worldwide Tax Summaries, Thailand corporate taxes (cross-check of SME conditions)
