TL;DR Corporate income tax in Thailand is generally charged at 20% of net taxable profit in 2026. Qualifying SMEs may benefit from progressive rates of 0% on the first THB 300,000, 15% on profits from THB 300,001 to THB 3 million, and 20% above this amount. Large multinational groups with consolidated revenue of at least EUR 750 million may also be subject to Thailand’s 15% global minimum top-up tax.
BOI-promoted companies may receive corporate income tax exemptions of three to eight years, although the benefit may be reduced for multinational groups covered by the global minimum tax. Companies must also file the half-year PND 51 return and annual PND 50 return on time, as underestimating profits, filing late or failing to prepare audited financial statements can result in significant penalties.
Introduction:
Corporate income tax in Thailand is generally charged at 20% of a company’s net taxable profits. However, the applicable rate depends on the business. Qualifying SMEs benefit from progressive rates of 0% on the first THB 300,000 of net profits, 15% on the next THB 2.7 million, and 20% on profits exceeding THB 3 million. Large multinational enterprise groups may also be subject to Thailand’s 15% global minimum tax under the OECD Pillar Two framework.
Tax treatment also varies according to a company’s tax residency, ownership structure, business activities and eligibility for investment incentives. For example, BOI-promoted companies may qualify for corporate income tax exemptions, while foreign companies without a permanent establishment in Thailand are generally taxed through withholding tax on certain Thai-sourced income.
With Thailand continuing to implement the global minimum tax and increasing international tax transparency, cross-border businesses should review their tax position early rather than waiting until year end.
Lex Nova Partners advises foreign investors on Thailand’s corporate tax rules through its tax services in Thailand, as part of an integrated legal, tax, investment and immigration service.
Key Points
- The standard corporate income tax rate is 20% of net taxable profit, with reduced progressive rates available to qualifying SMEs.
- Thailand’s 15% global minimum tax applies only to large multinational groups with consolidated revenue of at least EUR 750 million.
- BOI promotion may provide a three-to-eight-year tax exemption, but large multinational groups may still face top-up tax where their effective rate falls below 15%.
- Companies must file both PND 51 and PND 50 returns, with PND 50 generally due within 150 days of the accounting year-end.
- Late filing, underestimating profits or missing audited accounts can trigger substantial penalties, surcharges and additional tax assessments.
What Is the Corporate Income Tax Rate in Thailand?
The standard corporate income tax rate in Thailand is 20% of net taxable profit. This rate applies to companies incorporated under Thai law and foreign companies carrying on business in Thailand.
Corporate income tax is not calculated on gross revenue. It is calculated on taxable profit after allowable business expenses, deductions, depreciation and other permitted adjustments have been applied.
A company’s accounting profit may therefore differ from the amount of profit subject to corporate income tax. Certain expenses recorded in the financial statements may not be deductible for tax purposes, while other items may be treated differently under Thai tax law.
Foreign investors must also consider withholding tax, value added tax, transfer pricing, payroll obligations and whether a double tax treaty affects payments made across borders.
How much corporate income tax do SMEs pay in Thailand?
Eligible small and medium-sized enterprises may pay corporate income tax at reduced progressive rates rather than the standard 20% rate on all taxable profit.
To qualify, a company is required to have paid-up capital of no more than THB 5 million and annual revenue of no more than THB 30 million.
If the company satisfies both conditions, it is eligible for the following rates.
The first THB 300,000 of net taxable profit is exempt from corporate income tax. A CIT rate of 15% then applies to the net profit from THB 300,001 to THB 3,000,000 before the standard 20% rate applies to profit above THB 3,000,000.
The SME regime, based on Royal Decree No. 530 and subsequent amendments, does not automatically exclude Thai-incorporated companies with foreign ownership, provided they meet the relevant qualifying conditions.
What withholding tax applies to foreign companies not doing business in Thailand?
A foreign company that does not carry on business in Thailand may still be subject to withholding tax on income received from Thai sources.
The applicable rate depends on the type of income. Thai-sourced service fees, royalties, interest and certain other payments are generally subject to withholding tax at 15%, while dividends are generally subject to withholding tax at 10%.
A double tax treaty may reduce the rate or change how the income is taxed. The protections on offer depend on the treaty, the nature of the payment, the foreign company’s tax residence and whether the company has a permanent establishment in Thailand.
Foreign investors should therefore review both Thailand’s domestic rules and the relevant treaty before setting up payment arrangements. This is especially important when structuring management fees, technical service fees, royalties, financing arrangements or dividend payments.
The company’s wider structure should also be assessed alongside Thailand’s rules on foreign business ownership in Thailand, as tax and corporate law issues frequently overlap.
How Is Corporate Income Tax Calculated in Thailand?
Corporate income tax in Thailand is calculated on a company’s net taxable profit, rather than its total income or sales revenue. The calculation is based on the company’s accounting profit, which is then adjusted to reflect the deductions and restrictions imposed under Thai tax law.
The basic calculation is:
Total revenue − allowable business expenses + non-deductible expenses and other tax adjustments = net taxable profit
The applicable corporate income tax rate is then applied to the resulting taxable profit.
Step 1: Determine the Company’s Total Revenue
The company must first calculate all income earned during the relevant accounting period. Depending on its activities, this may include:
- Revenue from the sale of goods
- Income from providing services
- Rental income
- Interest income
- Commissions and management fees
- Other income connected with the business
The calculation should include all income that must be recognised during the accounting period, even where the timing of an invoice or payment differs from the date the income was earned.
Step 2: Deduct Allowable Business Expenses
The company can generally deduct expenses that are necessary for, and directly connected with, carrying on its business.
Common deductible expenses may include:
- Employee salaries, bonuses and benefits
- Office rent and utility costs
- Marketing and advertising expenses
- Legal, accounting and professional fees
- Business travel and transportation costs
- Interest paid on qualifying business loans
- Depreciation of equipment and other business assets
- Insurance and ordinary operating expenses
A business expense is not automatically deductible simply because it appears in the company’s accounts. The company should retain invoices, receipts, contracts and other supporting records showing that the expense was incurred for a genuine business purpose.
Step 3: Adjust for Non-Deductible Expenses
Some expenses recorded for accounting purposes cannot be deducted when calculating corporate income tax in Thailand. These amounts must be added back to the company’s accounting profit.
Examples may include:
- Personal expenses paid for shareholders or directors
- Corporate income tax payments
- Tax fines, penalties and surcharges
- Expenses unrelated to the company’s business
- Certain provisions or reserves
- Expenses that exceed statutory limits
- Payments without adequate supporting documents
These adjustments explain why a company’s taxable profit may be higher than the profit shown in its financial statements.
Step 4: Apply the Relevant Corporate Income Tax Rate
Once the required adjustments have been made, the remaining amount is the company’s net taxable profit.
A general company will normally apply the standard 20% corporate income tax rate. Qualifying small and medium-sized enterprises may instead apply the progressive SME rates to different portions of their taxable profit.
Any half-year corporate income tax already paid through Form PND 51 is then credited against the final annual liability calculated in Form PND 50.
How does withholding tax work and why do tax certificates matter?
Withholding tax is a prepayment of corporate income tax collected at source. When a Thai company pays another Thai company or an individual for services, rent, professional fees and certain other items, it must deduct tax from the payment and remit it to the Thai Revenue Department by the 7th of the following month (the 15th when filed online), using Form PND 3 for payments to individuals and Form PND 53 for payments to companies.
The common domestic rates are 1% on transport, 2% on advertising, 3% on services, professional fees and commissions, and 5% on rent. Payments to foreign companies that do not carry on business in Thailand are subject to the 15% rate described above (10% on dividends), subject to treaty relief.
For the company receiving the payment, the amount withheld is not a cost. It is tax paid in advance on its behalf, and it is deducted from the final corporate income tax liability in the annual PND 50 return, alongside the half-year PND 51 payment. Where the credits exceed the tax due, the excess can be claimed as a refund.
The credit is only available with the withholding tax certificate (Form 50 Tawi) issued by the payer. In practice, this is where companies lose money. A certificate that was never requested, or that arrives after the annual return has been filed, means tax has been paid twice. The accountant should therefore collect and reconcile withholding tax certificates every month, against the payments received, rather than chasing them at year end.
Worked Example: Calculating Corporate Income Tax at 20%
Consider a Thai company with the following results for its accounting year:
| Calculation | Amount |
| Total business revenue | THB 12,000,000 |
| Less: recorded business expenses | (THB 8,500,000) |
| Accounting profit | THB 3,500,000 |
| Add back: tax penalties | THB 50,000 |
| Add back: unsupported expenses | THB 150,000 |
| Net taxable profit | THB 3,700,000 |
The company’s corporate income tax is calculated as follows:
THB 3,700,000 × 20% = THB 740,000
The company’s annual corporate income tax liability is therefore THB 740,000, before deducting any eligible tax credits or corporate income tax already paid through the PND 51 half-year return.
This example uses the standard corporate income tax rate. A qualifying SME would need to apply the relevant progressive rates to each band of taxable profit rather than applying 20% to the full amount.
What Is the 15% Global Minimum Tax in Thailand and Who Does It Affect?
Thailand’s global minimum tax applies to multinational enterprise (MNE) groups with consolidated annual revenue of at least EUR 750 million in at least two of the previous four fiscal years. Established under the Emergency Decree on Top-up Tax B.E. 2567, published on 26 December 2024, the regime applies to financial years starting on or after 1 January 2025.
These rules apply only to qualifying large multinational groups. Most Thai SMEs, standalone foreign-owned companies and smaller international groups will not be affected.
The purpose of the global minimum tax is to ensure that large multinational groups pay an effective tax rate of at least 15% in each jurisdiction where they operate. Where the effective tax rate falls below 15%, a top-up tax may become payable.
Thailand’s regime includes three main mechanisms.
The Qualified Domestic Minimum Top-up Tax (QDMTT) allows Thailand to collect additional tax when the effective tax rate of an in-scope group’s Thai operations falls below 15%.
The Income Inclusion Rule allows the jurisdiction of a parent company to impose top-up tax in relation to low-taxed subsidiaries.
The Undertaxed Profits Rule can allocate additional tax to other jurisdictions when the Income Inclusion Rule has not fully collected the required amount.
The effective tax rate (ETR) is not the same as Thailand’s 20% corporate income tax rate. Under the Global Anti-Base Erosion (GloBE) Rules, the ETR is calculated using adjusted income and covered taxes. This means a group may pay corporate income tax at 20% but still need to calculate its GloBE ETR to determine whether a top-up tax applies.
The rules are particularly relevant where a multinational group benefits from a corporate income tax exemption, preferential tax treatment or significant differences between accounting and taxable income.
When do Thailand’s top-up tax filings and OECD data sharing start?
The first Global Anti-Base Erosion, or GloBE, filings for fiscal year 2025 are expected to be due by 30 June 2027.
Top-up tax returns will follow a separate filing timeline from normal corporate income tax returns. The standard filing period is 15 months after the end of the relevant fiscal year, with an 18-month period for the first year.
Thailand has also approved the automatic exchange of tax information with foreign tax authorities from June 2027. This will allow tax authorities to compare information concerning multinational groups across different jurisdictions.
The Thai Revenue Department expects the global minimum tax to generate approximately THB 10 billion in additional annual revenue.
Groups at or above the EUR 750 million threshold should not wait until 2027 to prepare. They may need to identify the relevant entities, collect jurisdictional tax data, assess safe harbours and review whether existing incentives could create a top-up tax exposure.
Smaller companies do not need to comply with the global minimum tax simply because they are foreign-owned. However, they may still be asked to provide information to a parent company if they form part of an in-scope multinational group.
Do BOI Companies Still Pay Corporate Income Tax in Thailand?
Companies promoted by the Thailand Board of Investment may receive a corporate income tax exemption for between three and eight years in most categories, and up to 13 years for certain high-technology activities, depending on the promoted activity, location, technology and wider economic benefit.
A BOI tax exemption can allow qualifying income from a promoted activity to be exempt from corporate income tax during the approved period. Some projects may also receive reductions after the exemption expires or additional deductions for eligible investments.
Not all BOI-promoted businesses qualify for a Corporate Income Tax (CIT) exemption. For example, companies operating under a TISO promotion do not receive this incentive. Eligibility for a CIT exemption, and the length of any exemption granted, depends on the company’s promoted business activities.
For companies below the EUR 750 million global minimum tax threshold, BOI tax incentives remain highly valuable. These businesses can benefit from Corporate Income Tax (CIT) exemptions without becoming subject to the 15% global minimum top-up tax.
However, this may not be the case for large multinational enterprise groups.
Where a BOI tax exemption reduces the effective tax rate of the Thai operation below 15%, the group may become liable for top-up tax. The corporate income tax holiday may therefore reduce tax paid under Thailand’s normal system while creating an additional liability under the global minimum tax rules.
This does not mean BOI promotion has become irrelevant. Promoted companies may still receive important non-tax benefits, including permission for 100% foreign ownership, land ownership rights, simplified visa and work permit procedures and customs incentives.
Thailand is also considering and developing alternative support for large multinational groups, including tax credits and grants through the BOI’s Competitiveness Enhancement Fund. These mechanisms may preserve the commercial value of investment incentives without reducing the effective tax rate in the same way as a traditional tax holiday.
A BOI tax exemption should not be viewed in isolation. The company’s BOI application, tax position and corporate structure should be considered together from the beginning, as the incentive may have wider implications for the group as a whole. This is where coordinating the BOI file with corporate law and M&A services makes a practical difference.
When and How Do You File Corporate Income Tax in Thailand?
Companies in Thailand file two corporate income tax returns each year: a half-year return and an annual return.
What is the Half-Year Corporate Income Tax Return?
The Half-Year Corporate Income Tax Return (PND 51) is an advance payment of corporate income tax made during the financial year. It is not an additional tax. Instead, the tax paid is credited against the company’s final Corporate Income Tax liability when the Annual Corporate Income Tax Return (PND 50) is filed.
Most companies calculate the PND 51 based on their estimated annual net profit, although certain businesses may calculate it using their actual net profit for the first six months where permitted under the Revenue Code.
Who Must File PND 51?
Most companies and juristic partnerships subject to Corporate Income Tax on their net profits are required to file a PND 51 return. A company in its first accounting period, where that period is shorter than 12 months, is not required to file it.
For companies with a calendar accounting year ending on 31 December, the filing deadline is 31 August each year (or 8 days later when the return is filed and the tax paid online through the Thai Revenue Department’s e-filing system). Businesses with a different financial year must file within two months after the end of the first six months of their accounting period.
How Much Tax Must Be Paid?
The PND 51 requires companies to estimate their annual taxable profit and calculate Corporate Income Tax on that estimate. The company then pays approximately 50% of its estimated annual Corporate Income Tax liability as a mid-year tax payment.
This payment is treated as a tax credit and deducted from the final Corporate Income Tax payable when the Annual Corporate Income Tax Return is submitted.
What Happens if the Profit Estimate Is Too Low?
Many businesses mistakenly treat the PND 51 as a simple estimate. However, the Revenue Department expects companies to make a reasonable assessment based on the information available at the time.
If the estimated net profit is more than 25% lower than the company’s actual net profit at year-end without reasonable justification, the company may be liable for an additional 20% surcharge on the tax shortfall. Late filing or payment may also result in fines and a surcharge of 1.5% per month on the unpaid tax.
Rather than relying on rough projections, companies should prepare updated management accounts before submitting the return to help ensure their estimate is reasonable.
Annual Corporate Income Tax Return (PND 50)
The Annual Corporate Income Tax Return (PND 50) is the company’s final Corporate Income Tax return for the accounting year.
Unlike the PND 51, which is based on estimated profits, the PND 50 is prepared using the company’s final audited financial statements. It reconciles the company’s actual taxable profit, calculates the final Corporate Income Tax liability, and deducts any tax already paid through the Half-Year Corporate Income Tax Return.
When Must the Annual Return Be Filed?
The Annual Corporate Income Tax Return must be submitted within 150 days after the end of the company’s accounting period.
For companies with a financial year ending on 31 December, both the PND 50 and the Corporate Income Tax payment are generally due by 30 May of the following year (or 8 days later for returns filed and paid online).
The Annual Closing Process
Preparing the Annual Corporate Income Tax Return involves considerably more than completing a tax form.
Before the return can be filed, the company must complete its year-end accounting records, prepare its financial statements, undergo a statutory audit by a licensed Certified Public Accountant (CPA), obtain shareholder approval where required, and submit its audited financial statements to the relevant government authorities.
The Corporate Income Tax Return is prepared using these final audited figures, making the annual closing process one of the most important compliance exercises of the year.
What happens if you file late or underpay?
Failing to meet Thailand’s Corporate Income Tax and annual closing requirements can result in significant financial penalties for both the company and its directors.
If a company fails to hold its Annual General Meeting (AGM) and approve the audited financial statements within four months of the financial year-end, as required by Section 1197 of the Civil and Commercial Code, the company may be fined up to THB 20,000 and each responsible director up to THB 50,000 under the Act Prescribing Offences Relating to Registered Partnerships, Limited Partnerships, Limited Companies, Associations and Foundations B.E. 2499.
Companies that fail to submit their audited financial statements to the Department of Business Development may be fined up to THB 50,000 under Section 30 of the Accounting Act B.E. 2543, and the managing director is liable to the same fine under Section 40. Financial statements that have not been audited by a licensed auditor expose the company to a further fine of up to THB 20,000 under Section 32. In practice, the DBD applies a settlement scale of THB 1,000 to THB 6,000 each for the company and the director depending on the delay, but the statutory ceilings apply where the matter is not settled. Under the Revenue Code, filing the PND 50 without the financial statements attracts a fine of up to THB 2,000 under Section 35, in addition to the 1.5% monthly surcharge on unpaid tax under Section 27. In addition, the Revenue Department may conduct a tax audit or issue additional tax assessments.
Where a company fails to prepare audited financial statements to support its Half-Year (PND 51) or Annual (PND 50) Corporate Income Tax returns, the Revenue Department has the authority to assess Corporate Income Tax based on 5% of either the company’s total gross income or gross sales before expenses, whichever is higher, rather than its actual taxable profits.
For the Half-Year Corporate Income Tax Return (PND 51), companies are expected to make a reasonable estimate of their annual taxable profit. If the estimated profit is more than 25% lower than the final taxable profit without reasonable grounds, a 20% penalty may be imposed on the tax shortfall. Additional penalties of 100% for filing an incorrect return or 200% for failing to file the return may also apply, although these penalties may be reduced, in some cases substantially, where the taxpayer files voluntarily and cooperates with the Thai Revenue Department.
How Can Foreign Investors Reduce Corporate Income Tax in Thailand Legally?
Foreign investors can reduce corporate income tax in Thailand through proper planning, provided the arrangements have a genuine commercial purpose and comply with Thai law.
Obtaining a BOI promotion is one of the most valuable options. Qualifying projects may receive a corporate income tax exemption, reduced tax, import duty incentives and non-tax benefits.
Smaller companies may benefit from the SME progressive rates if they remain within the paid-up capital and revenue thresholds. Business owners should monitor these thresholds before increasing capital or expanding revenue.
Double tax treaties can reduce withholding tax and help prevent the same income from being taxed twice. Treaty eligibility should be reviewed before entering into cross-border service, royalty, financing or dividend arrangements.
Companies can also improve their tax position through proper deductible expense planning. Expenses should be connected to the business, supported by valid documentation and recorded in the correct accounting period.
The last quarter of the accounting year is the right time to review this. Before the year closes, management should check which deductible expenses can still be incurred in the current year, such as staff bonuses, training, maintenance or marketing, and whether planned investments in equipment or software should be brought forward so that depreciation starts in the current period. Thailand also grants enhanced deductions from time to time, for example for certain training, research or investment expenses, and these are only useful if the spending is made and documented before year end.
For groups with activities outside Thailand, structure matters as much as timing. Where services are genuinely performed outside Thailand and sold to clients outside Thailand, the group may locate that activity in a jurisdiction with a lower corporate tax rate, such as Hong Kong or Singapore. This is a legitimate choice, but only with substance. If the foreign entity is in reality managed from Thailand, with no staff, office or decision-making of its own, the Thai Revenue Department may treat it as carrying on business in Thailand through a permanent establishment under Section 76 bis of the Revenue Code and tax its profits here, and any charges between the entities fall under Thailand’s transfer pricing rules in Section 71 bis. Each structure should be assessed on its facts, with the commercial activity, the people and the paperwork in the same place.
Special economic zones and regional incentive programmes may provide additional benefits. Investors considering projects outside Bangkok should review available tax incentives in Thailand’s Southern Special Economic Zones as well as incentives in the Eastern Economic Corridor.
Tax planning should be based on substance rather than artificial arrangements. This is increasingly important as Thailand expands international information exchange and applies greater scrutiny to multinational structures.
Lex Nova Partners also provides bilingual English and French advice, allowing French-speaking investors to discuss treaty, structuring and compliance issues in their preferred language.
FAQ – Frequently Asked Questions About Corporate Income Tax in Thailand
What is the corporate income tax rate in Thailand in 2026?
The standard corporate income tax rate in Thailand is 20% of net taxable profit in 2026. Qualifying SMEs may benefit from reduced progressive rates, while large multinational groups may also be subject to the 15% global minimum top-up tax.
Do small companies pay less corporate income tax in Thailand?
Yes. Qualifying companies with paid-up capital of no more than THB 5 million and annual revenue of no more than THB 30 million may benefit from progressive SME rates, including a 0% rate on the first THB 300,000 of net profit. A rate of 15% then applies to the net profit from THB 300,001 to THB 3,000,000 before the standard 20% rate applies to profit above THB 3,000,000.
When is corporate income tax due in Thailand?
The annual PND 50 corporate income tax return is generally due within 150 days of the end of the accounting period. Companies must also file the half-year PND 51 return within two months after the first six months of the accounting period.
Do BOI-promoted companies pay corporate income tax in Thailand?
BOI-promoted companies may receive a corporate income tax exemption for three to eight years, depending on the promoted activity. Large multinational groups may still face top-up tax if the exemption reduces their effective tax rate below 15%.
What is the 15% global minimum tax in Thailand?
Thailand’s 15% global minimum tax is a top-up tax regime for multinational groups with consolidated annual revenue of at least EUR 750 million. It ensures that covered groups pay an effective tax rate of at least 15% in each jurisdiction.
Does a foreign company pay corporate income tax in Thailand?
A foreign company carrying on business in Thailand is generally subject to corporate income tax at 20% on profits connected with its Thai operations. A foreign company not carrying on business may instead be subject to withholding tax on certain Thai-sourced income.
What happens if I file my corporate income tax return late in Thailand?
Late filing can result in fines, monthly surcharges on unpaid tax and additional penalties for incorrect or incomplete returns. The Thai Revenue Department may also request supporting documents or investigate the company’s tax calculations.
Getting Corporate Income Tax Right in Thailand
Corporate income tax in Thailand requires more than simply applying the standard 20% rate. Companies must check whether they qualify for SME rates, meet annual and half-year filing deadlines and assess whether BOI promotion or the global minimum tax changes their effective position.
For large multinational groups, the interaction between BOI tax incentives and the 15% top-up tax requires particular attention. For smaller businesses, accurate accounting, proper deductions and timely filings remain the main priorities.
Lex Nova Partners coordinates tax, corporate, BOI, immigration and employment matters through one team. Advice is available in English, Thai and French.
To discuss your Thailand corporate income tax position, schedule a consultation with our Bangkok office.
This article is general information, current as of October 2026, and does not constitute tax or legal advice. Last updated: October 2026.
Please note that this article is for information purposes only and does not constitute legal advice
