Personal Income Tax Filing in Thailand for Expats: A Practical Guide for 2026

Filing personal income tax in Thailand can be confusing for foreign residents, and as the 2026 personal income tax (PIT) season is upon us, we have compiled this guide to explain who must file, what income is assessable, and how to navigate the filing process for tax year 2025.

The regulatory framework affecting expats shifted in January 2024 with the issuance of Revenue Department Orders Por.161/2566 and Por.162/2566. Under these orders, Thai tax residents must pay income tax on foreign income earned from January 1, 2024 onward, when that income is remitted to Thailand. This marked a departure from the previous interpretation, which permitted foreign income to escape Thai taxation under certain conditions.

Thai Tax Residency and Filing Thresholds

Thai tax residency is determined by physical presence, not visa category or immigration status. Any individual who spends 180 days or more in Thailand during a calendar year qualifies as a tax resident for that year. Partial days count as full days for this calculation. The tax year aligns with the calendar year, running from January 1 to December 31, and residency status is assessed each year.

Tax residents must file a return if assessable income exceeds THB 120,000 per year for single individuals or THB 220,000 for married couples that are filing jointly.

Those who earn Thai-sourced income, such as salary from a Thai employer, rental income from Thai property, business profits generated within the country, must file and pay tax on that income regardless of days spent in Thailand. Foreign-sourced income falls outside the Thai tax net for non-residents entirely.

Assessable Income: Thai-Sourced and Foreign-Sourced

Thailand's personal income tax operates on two foundational principles: the source rule and the residence rule. Under the source rule, income derived from activities, assets, or employment within Thailand is taxable regardless of the recipient's residency status or where payment is received. Under the residence rule, Thai tax residents face potential liability on foreign-sourced income when that income enters the country.

Thai-sourced income encompasses employment income from Thai employers, business profits from operations conducted in Thailand, rental income from Thai property, dividends from Thai-registered companies, and capital gains from the disposal of Thai assets.

Foreign-sourced income follows different mechanics. For tax residents, such income becomes assessable when remitted to Thailand. This covers employment income from overseas employers, pension payments from foreign sources, investment returns including dividends, interest, and realized capital gains, rental income from overseas property, and freelance or consulting income earned abroad. The timing of when income was earned now determines the taxability. Income earned on or after January 1, 2024 is subject to Thai tax when brought into the country.

Thai Tax Rates and Liability Reduction

Thailand applies a progressive tax structure with rates ranging from 0% to 35%, calculated on net income after deductions and allowances. The first THB 150,000 of net income is exempt, with marginal rates increasing through eight brackets.

Net Income (THB)	Tax Rate
0 – 150,000	0% (exempt)
150,001 – 300,000	5%
300,001 – 500,000	10%
500,001 – 750,000	15%
750,001 – 1,000,000	20%
1,000,001 – 2,000,000	25%
2,000,001 – 4,000,000	30%
Over 4,000,000	35%

The progressive structure means each bracket applies only to income within that range. An individual with THB 500,000 in net income (assuming no deductions) pays 0% on the first THB 150,000, 5% on income from THB 150,001 to THB 300,000 (THB 7,500), and 10% on income from THB 300,001 to THB 500,000 (THB 20,000), yielding a total tax of THB 27,500, which is an effective rate of 5.5%.

Deductions and Allowances

Foreign nationals qualify for most deductions available to Thai citizens. The personal allowance stands at THB 60,000, with an additional THB 60,000 available for a spouse without income and THB 30,000 per child. Employment income attracts a standard expense deduction of 50% of income, capped at THB 100,000.

Additional deductions apply to life insurance premiums up to THB 100,000, health insurance premiums up to THB 25,000 where the policy is issued by a Thai-registered insurer, provident fund contributions up to 15% of salary capped at THB 500,000, and Retirement Mutual Fund and Super Savings Fund contributions subject to a combined cap of THB 500,000. In practice, the deduction regime favors individuals with Thai-denominated financial products. As such, international health insurance policies and overseas retirement accounts generally do not qualify.

Double Taxation Agreements

Thailand maintains Double Taxation Agreements with 61 countries, covering major economies including the United States, United Kingdom, Australia, Canada, Germany, France, Japan, and Singapore. These treaties allocate taxing rights between jurisdictions and provide mechanisms to prevent the same income from being taxed twice.

Under most agreements, where foreign income has already been taxed in the source country, Thai residents may claim a foreign tax credit against their Thai liability. Claiming treaty benefits requires a Certificate of Tax Residency from the foreign tax authority, evidence of foreign tax paid, and a declaration of both the foreign income and taxes paid on the Thai return. The Revenue Department publishes further details on double taxation agreements.

The Filing Process

Obtaining a Tax Identification Number

A Thai Tax Identification Number is required before filing. Individuals employed in Thailand typically receive a TIN through their employer's registration process. Those without employment must apply in person at the Revenue Department office responsible for their residential district.

The application requires a valid passport with a current visa, proof of Thai address such as a TM30 notification receipt. Applicants must submit Form L.P. 10.1 at the correct district office. The correct district office is based on the applicant´s residence or working address. Applications that are filed at other branches will be rejected. Revenue officers cross-reference the submitted address against immigration records, so ensuring the TM30 notification is current reduces the risk of rejection.

Selecting the Correct Form

Thailand uses different forms depending on income composition. Form PND 91 applies to individuals whose income derives solely from employment. Form PND 90 covers individuals with multiple income sources, including self-employment, rental income, investment returns, or foreign income remittances. Most expats with foreign-sourced income will require PND 90. A mid-year return, Form PND 94, applies to certain non-salary income categories and is due by September 30, with tax paid credited against the annual liability.

Filing Methods and Deadlines

Returns may be submitted electronically through the Revenue Department portal or in person at local Revenue Department offices. Electronic filing requires account registration using the TIN and offers an extended deadline by up to 8 days. In-person filing does not guarantee English assistance, and bringing a Thai speaker or engaging a tax agent is advisable.

Filing Method	Deadline
Annual return (PND 90/91) – paper filing	March 31, 2026
Annual return (PND 90/91) – electronic filing	April 8, 2026
Mid-year return (PND 94) – paper filing	September 30, 2026
Mid-year return (PND 94) – electronic filing	October 8, 2026

Payment is due by the filing deadline. Options include electronic payment through the Revenue Department portal, payment at authorized banks, or payment at Revenue Office counters. Where tax liability exceeds THB 3,000, taxpayers may apply to pay in up to three monthly installments without surcharge.

Penalties for Non-Compliance

Non-compliance carries escalating consequences. Late filing attracts a fine of up to THB 2,000 per return. Late payment triggers a surcharge of 1.5% per month on the outstanding amount, accumulating to a maximum of 100% of the tax owed. Filing an inaccurate return may result in penalties of 100% of the underpaid tax, while failure to file can attract penalties of 200%. Deliberate evasion exposes taxpayers to criminal prosecution with potential imprisonment.

Thailand's participation in the OECD Common Reporting Standard (CRS) increases detection risk. Under CRS, financial institutions in over 130 participating jurisdictions exchange account information automatically with tax authorities, enabling the Revenue Department to cross-reference declared income against foreign account data.

Common Issues for Expat PIT Compliance

Several recurring issues complicate expat tax compliance. Reliance on employer withholding as complete compliance is a frequent error. Employers are obligated to withhold tax on salary but have no visibility into employees' foreign income, investment returns, or rental income. Where additional income sources exist, the individual bears the responsibility for declaration.

Address documentation inconsistencies can delay TIN applications and complicate filing. The address shown on TM30 notifications and applications must be submitted to the Revenue Office with jurisdiction over that address. Many expats also overlook available Double Taxation Agreement benefits, paying more Thai tax than legally required because the Revenue Department does not automatically apply treaty credits when the taxpayers do not claim them.

Conclusion

A proposed two-year exemption window for foreign income remittances has been discussed by the Revenue Department but remains unenacted. Until such changes are published in the Royal Gazette, taxpayers should plan based on current rules.

BizWings Thailand is a Bangkok-based accounting and advisory firm serving foreign SMEs operating in or entering the Thai market. Our team works with expats across a range of compliance matters, including personal income tax registration and return preparation. With annual filing deadlines falling in late March and early April, those requiring assistance for tax year 2025 should direct inquiries to our team by mid-February to allow adequate preparation time.

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