Thailand Corporate Income Tax in 2026: Rates, PND.50 and PND.51 Deadlines

For companies operating in Thailand, corporate tax is not simply a year-end task. Businesses generally need to plan for a mid-year tax payment, an annual return, accounting records, audited financial statements and several other recurring filings.

The good news is that Thailand corporate income tax is relatively straightforward once you understand the main rate and filing cycle. The standard corporate income tax rate remains 20% of net profit, while qualifying SMEs and BOI-promoted businesses may receive lower rates or exemptions.

Here is what business owners need to know about the Thailand corporate tax rate 2026 and the key deadlines.

Key takeaways

The standard Thailand corporate income tax rate is 20% of net taxable profit.

Qualifying SMEs can receive a 0% rate on their first THB 300,000 of net profit and a 15% rate on the portion between THB 300,001 and THB 3 million.

PND.51 is the half-year corporate income tax filing and advance payment.

PND.50 is the final annual corporate income tax return.

For businesses with a 31 December year-end, the 2026 PND.50 deadline is 2 June 2026 for paper filing and 8 June 2026 for online filing.

For calendar-year companies, PND.51 is due 31 August 2026 on paper or 8 September 2026 online.

The 20 percent standard rate

The standard corporate income tax rate in Thailand is 20% of net taxable profit. Tax is calculated after allowable business expenses and other permitted deductions have been applied.

This distinction matters. A company earning THB 10 million in revenue does not automatically pay THB 2 million in corporate tax. Corporate income tax is normally based on taxable profit rather than gross revenue.

Good bookkeeping therefore directly affects tax compliance. Expenses must be properly recorded and supported and year-end figures need to reconcile with the company's accounts. Businesses that want ongoing support can use professional accounting services to manage bookkeeping, tax calculations, PND filings and year-end reporting.

SME reduced brackets table

Thailand provides reduced corporate income tax rates for qualifying smaller companies. The relevant rules apply where paid-up capital at the end of the accounting period does not exceed THB 5 million and revenue from sales and services does not exceed THB 30 million.

Net taxable profit

Corporate income tax rate

THB 0–300,000

0%

THB 300,001–3,000,000

15%

Above THB 3,000,000

20%

The reduced rates apply in bands. Crossing THB 3 million of profit does not mean the company's entire profit suddenly becomes taxable at 20%.

BOI tax holidays

Companies promoted by Thailand's Board of Investment may receive significant corporate tax incentives.

Depending on the promoted activity, a BOI project may qualify for a corporate income tax exemption for up to eight years. Certain projects involving advanced innovation can receive exemptions lasting up to 13 years. The exact benefit depends on the activity, investment conditions, promotion certificate and any applicable exemption cap.

Importantly, BOI promotion does not mean a business can ignore its accounting and tax administration. Companies still need proper records and must comply with the conditions attached to their promotion.

Half-year PND.51

PND.51 is effectively an advance corporate income tax payment.

A company generally estimates its annual net profit, calculates the expected tax and pays half of the estimated annual tax liability. The filing is due within two months after the end of the first six months of the accounting period. The amount paid is later credited against the company's final annual tax liability.

For companies running from 1 January to 31 December, the Thailand tax filing deadline 2026 for PND.51 is 31 August for paper filing or 8 September for online filing.

Annual PND.50

PND.50 is the company's final annual corporate income tax return. It uses the company's actual results rather than the estimate made for PND.51.

The statutory rule requires PND.50 to be filed within 150 days after the accounting year ends.

For companies whose 2025 accounting period ended on 31 December, the Revenue Department set the 2026 filing deadline at 2 June 2026 for filing at the Revenue Office, reflecting the calendar of holidays, while eligible online filing receives an extension to 8 June 2026.

Companies with a different financial year-end should calculate their deadline from their own accounting period rather than using the calendar-year dates.

Penalties

Missing a tax deadline can quickly become expensive. Unpaid tax can attract a surcharge of 1.5% per month or part of a month. Late PND.50 filing can also result in a fine of up to THB 2,000.

PND.51 creates another risk. If a company underestimates annual net profit by more than 25% without reasonable cause, a 20% surcharge can apply to the tax shortfall.

This is why PND.51 should be treated as a real forecasting exercise rather than a rough estimate made immediately before filing.

Compliance calendar link

Corporate income tax is only part of a Thai company's compliance workload. Depending on the business, monthly obligations can also include withholding tax, VAT and Social Security filings.

See Settlr's full calendar for the main 2026 PND.1, PND.3, PND.53, PP.30, PND.50, PND.51 and Social Security deadlines.

FAQs

What is the Thailand corporate tax rate in 2026?

The standard rate is 20% of net taxable profit, although qualifying SMEs and businesses receiving BOI incentives may pay lower effective rates.

What is the difference between PND.50 and PND.51?

PND.51 is the half-year estimate and advance corporate tax payment. PND.50 is the final annual return based on actual financial results. Tax already paid through PND.51 can be credited against the final liability

Does a company still file if it makes a loss?

Companies generally continue to have corporate tax filing obligations even when no corporate income tax is payable. Proper records are also important because qualifying tax losses may affect future tax calculations.

How can I avoid missing Thailand tax deadlines?

Maintain monthly books, review tax estimates before PND.51 and keep annual audit and PND.50 preparation on a calendar rather than waiting until year-end.

Want every key filing date in one place? Download the tax calendar and plan your 2026 compliance schedule before the next deadline.

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