BANGKOK – Many expats struggle to determine whether they’re Thai tax residents, whether foreign income becomes taxable after it reaches Thailand, and whether they should file PND 90 or PND 91. The answer depends on details such as your days in Thailand, the type of income you received, and when you earned and remitted it.
This guide focuses on the 2025 tax year, filed in 2026, and explains who must file, how the 180-day residency test works, when remitted foreign income may be taxable, how to calculate and pay tax online, and what can happen if your return is late. It also covers PND 90 and PND 91 tax returns, while noting that deadlines and rules can change. Use this as general information, not personal tax advice, then start by checking your Thai tax residency status.
Key Takeaways
- Spend 180 days or more in Thailand during a calendar year, and you generally become a Thai tax resident, even if your stays are not consecutive.
- Foreign income earned from 2024 onward may become taxable when you remit it to Thailand. Keep records showing when you earned and transferred the money.
- Use PND 91 for salary-only income. If you have freelance, rental, investment, or other assessable income, PND 90 is usually the correct return.
- For the 2025 tax year, the reported deadlines are March 31, 2026, on paper, and April 8, 2026, online.
- Review Thailand’s foreign income tax rules before filing, especially if your savings include money earned before 2024.
Who Must File Thai Income Tax (PND 90/91)?
Thailand’s personal income tax applies to assessable income, meaning income the Revenue Code recognizes for taxation. It can include salary, freelance fees, business profits, rent, interest, dividends, pensions, and certain foreign earnings. The Revenue Department’s personal income tax guidance explains how Thai-source and foreign-source income can fall within the tax system.
The 180-Day Tax Residency Test
You generally become a Thai tax resident when you spend 180 days or more in Thailand during a calendar year, from January 1 through December 31. The days do not need to be consecutive. Residency depends on your physical presence, not your visa type, nationality, work permit, or whether you own a home in Thailand.
A tourist who stays long enough can meet the test, while a long-term visa holder who spends fewer than 180 days may not. However, tax residency and filing obligations are separate questions. Even a nonresident may need to report Thai-source income.
Thai residents generally pay tax on Thai-source income and may also owe tax on foreign-source income brought into Thailand. A foreign bank account or overseas employer does not automatically remove Thai tax obligations.
Thai-Source and Foreign-Source Income
Thai-source income usually comes from work, business activity, property, or services connected with Thailand. Foreign-source income comes from activity or assets outside Thailand, such as overseas employment, foreign investments, or rental property abroad.
Under the current rule, foreign income earned on or after January 1, 2024 may become assessable when a Thai tax resident remits it to Thailand. That can apply even when the money arrives in a later tax year. Foreign income earned before January 1, 2024 is generally treated differently under current Revenue Department guidance.
Keep bank statements, travel records, payslips, investment statements, and evidence showing when you earned and transferred funds. These records help separate income from savings or capital. Tax treaties may change how particular income is taxed, but you should not assume a treaty applies without checking its terms. If you have salary only, PND 91 may fit; other assessable income usually requires PND 90.
PND 90 or PND 91? Choose the Right Thai Tax Return
The correct Thai tax return depends on the type of income you received during the year, not simply your job title or whether you are an expat. PND 91 is limited to employment income under Section 40(1), while PND 90 covers broader or mixed income.
When to Use PND 91
Use PND 91 when your only assessable income comes from employment under Section 40(1). This generally includes salary, wages, bonuses, and similar employment income. The Revenue Department describes PND 91 as the return for taxpayers with only Section 40(1) employment income. You can review the official PND 91 form details before filing.
For example, an employee who receives one monthly salary from a Thai employer and has no rental, freelance, investment, or business income would normally file PND 91. The same applies if the employer already withheld income tax during the year.
However, withholding tax does not always settle your final annual liability. Your total income, deductions, allowances, and tax credits may produce additional tax or a refund when you file the annual return.
When PND 90 Is Required
PND 90 is the broader annual return for taxpayers with income beyond employment-only Section 40(1) income. It can cover business profits, freelance fees, rent, interest, dividends, pensions, and capital gains where applicable. It also applies when you combine salary with another assessable income type.
An employee who earns a salary and rents out a condominium, for example, would generally use PND 90. The same is true for an employee who receives freelance design fees, overseas pension income, or reportable investment income. RSM Thailand’s PND 90 and PND 91 guidance explains this employment-only versus mixed-income distinction.
PND 94 is separate. It is a midyear return for certain non-employment income earned during the first half of the year, such as qualifying business, professional, rental, or freelance income. It does not replace the annual PND 90 or PND 91 filing.
If you have mixed foreign income, stock sales, pensions, or an unclear income category, ask the Revenue Department or a qualified Thai tax adviser before submitting your return.
How Much Thai Personal Income Tax Will an Expat Pay?
Your Thai personal income tax depends on taxable income, not your gross pay alone. Start with assessable income, subtract permitted expense deductions, remove personal allowances and eligible deductions, then apply the progressive tax rates. You can review the Thai personal income tax rate table before preparing your return.
Thai Personal Income Tax Rates for 2025
For the 2025 tax year, the rates are:
| Taxable income | Rate |
|---|---|
| Up to 150,000 THB | 0% |
| 150,001 to 300,000 THB | 5% |
| 300,001 to 500,000 THB | 10% |
| 500,001 to 750,000 THB | 15% |
| 750,001 to 1,000,000 THB | 20% |
| 1,000,001 to 2,000,000 THB | 25% |
| 2,000,001 to 5,000,000 THB | 30% |
| Above 5,000,000 THB | 35% |
These rates apply only to the income within each band. Reaching the 20% bracket does not make all your income taxable at 20%.
Deductions and Allowances
Common reliefs can include the 60,000 THB personal allowance, a qualifying spouse allowance, child allowances, social security contributions, approved life or health insurance, retirement funds, mortgage interest, and qualifying donations. Employment income may also receive a permitted expense deduction, generally 50% up to the applicable maximum.
The limits and conditions can change, so confirm each amount for the relevant tax year. Thailand’s tax changes for expats may also affect how you review foreign income and available reliefs.
If you earned income in another currency, convert it into Thai baht using an accepted exchange rate. Use the same method consistently and retain the exchange-rate records with your bank statements and income documents.
Simple Worked Example
Assume these fictional figures:
- Gross assessable income: 1,200,000 THB
- Permitted expense deduction: 100,000 THB
- Personal allowance: 60,000 THB
- Taxable income: 1,040,000 THB
- Withholding already paid: 140,000 THB
The calculated tax is 155,000 THB: 7,500 THB at 5%, 20,000 THB at 10%, 37,500 THB at 15%, 50,000 THB at 20%, and 40,000 THB at 25%. After crediting withholding, the remaining balance is 15,000 THB.
How to File and Pay PND 90 or PND 91 in Thailand
Filing becomes easier when you gather your records before opening the online form. Use the Thailand tax filing guide to check the correct form, documents, and filing steps, then work through the checklist below.
Prepare Your Documents
Keep digital copies of these records:
- Your passport and Thai tax identification number.
- Your employer’s withholding certificate, usually the 50 bis certificate, plus salary slips and annual salary records.
- Bank statements showing interest, transfers, and money remitted to Thailand.
- Rental agreements, rental income records, business accounts, and freelance invoices.
- Foreign income statements, pension records, investment reports, and other evidence of overseas income.
- Remittance records showing when foreign funds entered Thailand.
- Exchange-rate calculations and the records supporting the rates you used.
- Receipts for insurance, retirement funds, approved investments, and donations.
- Proof of tax already withheld, including Thai withholding certificates and foreign tax payment records where relevant.
The Revenue Department provides tax-year forms and attachments. If you received a qualifying lump-sum termination payment and choose separate taxation, complete the separate PND 90/91 attachment for that payment. It can cover certain retirement, provident fund, pension, and severance amounts.
Submit the Return and Pay
For the 2025 tax year, the reported deadlines are March 31, 2026, for paper filing and April 8, 2026, for electronic filing. Confirm the current date on the Revenue Department website because filing deadlines can change.
Use the Revenue Department’s e-Filing or D-MyTax service to:
- Select PND 90 or PND 91 and the correct tax year.
- Enter your income, deductions, allowances, withholding, and foreign tax details.
- Review the calculated tax, refund, or balance due.
- Submit the return and save the confirmation number or receipt.
- Pay any balance through the payment options shown by the system.
If you can’t file online, visit a Revenue Office or appoint an authorized representative. When the result is a refund, keep your bank details current and retain every supporting record until the refund is processed and the filing period has closed.
Avoid These Common Expat Tax Mistakes and Late-Filing Penalties
Small filing errors can create larger problems when you report Thai income tax as an expat. Check your records carefully before choosing a form or classifying money transferred into Thailand.
Mistakes That Commonly Cause Errors
Counting visa validity instead of your actual days in Thailand is a frequent mistake. Tax residency depends on physical presence during the calendar year, not the length of your visa. Also, don’t ignore foreign income earned from 2024 onward simply because it was paid into an overseas account first.
A transfer between your own accounts isn’t automatically income. Savings, gifts, inheritances, loan proceeds, old capital, investment principal, pensions, and investment gains can receive different tax treatment. The result depends on the source, timing, and documents proving what the money represents. Keep bank statements, pension records, inheritance documents, loan agreements, and investment statements rather than labeling every remittance as taxable or exempt.
Other errors include:
- Choosing PND 91 after receiving rental income, freelance fees, investment income, or a pension.
- Forgetting to credit employer withholding shown on your 50 bis certificate.
- Mixing personal funds with business receipts, which makes income and expenses harder to verify.
- Claiming deductions without receipts or other supporting evidence.
- Losing records that show when foreign income was earned and remitted.
- Relying on social media claims about tax treaties without checking the treaty’s actual conditions.
Expats using a Destination Visa should also review Thailand DTV tax obligations instead of assuming the visa removes tax responsibilities.
Late Filing and Corrections
For the 2025 return, commonly cited consequences include a fine of up to 2,000 THB and a 1.5% monthly surcharge on unpaid tax, with a fraction of a month generally counted as a full month under Revenue Department rules. Confirm current instructions through the Revenue Department’s e-Service information.
Filing late can still reduce further problems when tax is owed. Submit the return and pay as soon as possible, then contact the Revenue Department promptly if you discover an error. Seek professional advice for high-value foreign income, business activity, overseas pensions, complex investments, or possible treaty relief.
Frequently Asked Questions
These questions often arise after you understand the basic residency rules, income categories, and filing deadlines. The correct answer can still depend on your documents, income source, and personal circumstances.
Do I need a Thai tax ID number to file?
You generally need a Thai taxpayer identification number for personal income tax filing, especially when registering for online services or reporting taxable income. If you don’t have one, contact a Thai Revenue Office before submitting your return, and bring your passport and supporting address or income documents. The Thai Revenue Department can confirm the registration process for your situation.
Can I file if I left Thailand before the deadline?
Yes, leaving Thailand before the filing deadline doesn’t automatically remove your filing obligation. You may be able to file through the online system, appoint an authorized representative, or submit documents through a Thai Revenue Office. Check whether your online account remains active, and confirm the available options with the Revenue Department before the deadline.
Is overseas salary taxable if I earned it before moving money to Thailand?
The timing of both the income and the remittance matters. Salary earned while you were a Thai tax resident may require careful review, even if you transferred it later, while income earned before becoming resident can receive different treatment. Keep employment records, bank statements, and transfer evidence, then ask a qualified adviser to assess the exact tax year and source.
Do retirees need to file a Thai tax return?
Retirement status alone doesn’t create an automatic filing exemption. A retiree may need to file if they receive assessable pension, rental, investment, business, or remitted foreign income. Review Thai tax rules for foreign retirees and confirm the filing requirement with the Revenue Department.
What should I do if I made a mistake on my submitted return?
Contact the Revenue Department promptly rather than submitting conflicting information or ignoring the error. Depending on the issue and filing status, you may need to submit a correction, provide additional documents, or pay extra tax and surcharge. A qualified Thai tax adviser can help with material errors involving foreign income, deductions, or tax credits.
Can my home-country tax reduce my Thai tax bill?
A foreign tax credit may reduce Thai tax on the same foreign-source income when a tax treaty allows it. The credit generally can’t exceed the Thai tax payable on that income, and you may need an official foreign tax payment certificate. Check the applicable treaty and keep proof of the income, tax paid, and exchange-rate calculation before claiming relief.
