Tax Filing in Thailand: Legal Procedures, Deadlines, and Compliance for Residents and Foreigners

Steuerkonzept mit US-Dollar-Scheinen und Schriftzug „TAXES“ – Symbol für Tax Filing Thailand.

Understanding tax filing in Thailand: who must pay and how the law applies to Foreign Residents

Paying taxes in Thailand is required by law. Tax filing means you must declare, calculate, and pay your income. If you earn money from work, business, or property in Thailand, you are required to file a tax return. The law also explains who counts as a tax resident and when foreign income is taxed if it is brought into Thailand in the same year.

Foreign residents, investors, and business owners must understand Thai tax laws to remain compliant and avoid double taxation or fines. Recent updates, such as new Revenue Department rules in 2566, have changed how foreign income is taxed and have affected many expatriates.

In this article, Benoit & Partners outlines the steps, deadlines, and legal implications of filing taxes in Thailand, referencing key provisions of the relevant laws. We also emphasize the importance of determining your tax status early and recommend reading our guide on tax residency for more information.

Table of Contents

What does tax filing in Thailand legally mean? 

The tax filing in Thailand refers to the annual submission of an income declaration to the Revenue Department. Pursuant to Section 56 of the Revenue Code, any person with assessable income must file a return showing the total income earned, applicable deductions, and taxes payable. The law also imposes a mid-year return requirement under Section 56 bis for specific business income categories, ensuring accurate tax collection throughout the fiscal year.

This filing may be performed in person at the Revenue Office or through the official electronic platform (e-filing). Regardless of the method, the declaration must be complete and truthful. Submitting an inaccurate return constitutes an offence under Section 37, which penalizes the concealment or misrepresentation of income.

Ultimately, the tax filing system in Thailand aims to ensure transparency, guarantee fair tax collection, and uphold fiscal discipline within the Kingdom. It is a central mechanism for maintaining public confidence in Thailand’s taxation framework and ensuring that everyone contributes according to their ability to pay.

Who is required to complete tax filing in Thailand? 

The obligation to carry out tax filing in Thailand depends primarily on two legal factors: the individual’s status and the source of income. These criteria determine whether a person must declare income derived from Thailand only, or also from abroad. The distinction is established under Section 41 of the Revenue Code, which defines who is considered a tax resident and what income falls within Thailand’s jurisdiction.

Tax residency and its consequences

Under Section 41, any person who stays in Thailand for at least 180 days during a calendar year is considered a tax resident.

A resident is required to declare all income earned both in Thailand and abroad, provided that any foreign-sourced income is transferred into Thailand within the same year it was earned.

This rule means residents are taxed on worldwide income only if the money is brought into Thailand in the same year. Expatriates and long-term foreign residents should be aware of this, as it affects what they need to report annually.

Non-residents’ obligations

Non-residents are subject to taxation solely on income arising from Thai sources. This includes salaries from employment in Thailand, profits from local business operations, rental income from Thai properties, or investment income generated within the country.

Non-residents do not meet the 180-day rule, so they are not taxed on foreign income, even if they send it to Thailand. They only pay tax on income and assets that are directly linked to Thailand.

Practical implications

Both residents and non-residents conducting economic activities in Thailand are required to comply with the tax filing process. Residents must report both domestic and remitted foreign income, while non-residents are obligated to declare only income sourced within Thailand.

Accurately determining tax residency status is essential, as it establishes the scope of taxable income and potential exposure to penalties for underreporting or misclassification. Legal counsel is frequently required to ensure full compliance with the Revenue Code and the interpretations provided by the Thai Revenue Department.

Assessable income and tax filing in Thailand under the Thai Revenue Code 

Under Section 40, assessable income encompasses all forms of compensation or benefits received in exchange for work, services, or capital. This includes salaries, bonuses, commissions, fees, rents, dividends, and profits. Thai law categorizes income into eight distinct types, each associated with specific reporting and withholding obligations.

For instance, income from employment is subject to progressive personal income tax rates ranging from 5% to 35%, while dividends from Thai companies are usually taxed at a final rate of 10%. Income derived from professional services, rents, or property sales must also be declared through the appropriate forms, generally PND 90 or PND 91, depending on the income structure.

Recent changes in the law confirm that foreign income is taxable if you bring it into Thailand in the same year it is earned. Before, people could wait to send money to avoid taxes, but this is no longer allowed.

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How to complete tax filing in Thailand online and on paper 

The Revenue Department of Thailand provides two main channels for fulfilling tax obligations: paper submission and electronic filing. The e-filing system, available through filing.rd.go.th, allows individuals to register using their taxpayer identification number or passport, submit declarations, and make payments digitally.

Taxpayers must select the correct form based on their income composition. Form PND 91applies to those who earn income solely from employment. Form PND 90is used when the taxpayer has multiple income sources, such as business profits, rental income, or dividends.

To file your taxes, enter your total income, apply any deductions, and check the final tax amount. You can pay online through partner banks or by QR code. After you finish, you get a digital receipt. The system is now easier and more efficient for everyone.

Advantages of the e-filing system

Over the past decade, Thailand has invested heavily in modernizing its tax infrastructure, making tax filing in Thailand more efficient and accessible than ever. The e-filing system minimizes administrative burdens for both taxpayers and authorities, reduces processing times, and enhances accuracy. The system enables users to file returns from any location, which is particularly advantageous for expatriates and business owners with diverse income sources. The shift from paper to digital filing demonstrates Thailand’s commitment to fiscal transparency and modernization.

Tax filing in Thailand deadlines and payment process 

The Thai tax year runs from January 1 to December 31. The annual filing must be completed by March 31 of the following year, in accordance with Section 56. For online submissions, the deadline is generally extended until April 8, providing additional time to finalize declarations.

For those subject to mid-year tax filing, Section 56 bis requires submission before September 30. These deadlines are strict, missing them automatically triggers penalties. According to Section 89 bis, an interest of 1.5% per month applies to unpaid taxes, while a separate fine of up to 2,000 THB may be imposed for late filing.

You need to pay your taxes when you file your return. If you pay too much, you can ask for a refund within three years. Keep all your receipts and payment records, as the Revenue Department may ask to see them.

Penalties for late or incorrect tax filing in Thailand 

Thai law imposes both administrative and criminal sanctions for failure to comply with tax filing obligations in Thailand. Late submission or non-submission exposes the taxpayer to fines and interest charges. Under Section 37, intentional concealment or false declarations can result in imprisonment for up to seven years and a fine equivalent to double the unpaid tax amount, as specified in Section 90.

Even small mistakes can be expensive. The Revenue Department checks for errors or repeated late filings. If you do not comply, you may face travel restrictions or difficulties renewing work permits and visas, as tax records are reviewed by immigration. Always file your taxes correctly and on time.

Deductions, exemptions, and relief under tax filing in Thailand 

The Revenue Code recognizes a range of deductions and allowances designed to ease the tax burden for individuals. Section 47 bis authorizes a standard deduction of 50% on employment income, capped at 100,000 THB, while Section 47 ter provides a personal allowance of 60,000 THB per taxpayer. Additional allowances exist for spouses, dependent children, and parents, as well as for insurance premiums and charitable donations.

For business operators, Sections 65 and 65 bis define legitimate expenses that are deductible from gross income, including operating costs and depreciation. Proper documentation is vital, as unsupported deductions are routinely disallowed during audits.

Understanding how these rules work helps you file your taxes accurately and avoid potential issues. Many people seek help from legal advisors to organize their income and deductions and ensure compliance with all requirements.

Double taxation agreements and their impact on tax filing in Thailand 

Thailand’s network of Double Taxation Agreements (DTAs), authorized by Section 3 ter, prevents income from being taxed twice when it arises in a partner country. These agreements define taxing rights between jurisdictions and often provide exemptions or credits.

During the tax filing process in Thailand, residents of Double Taxation Agreement partner countries may claim relief by submitting a valid Certificate of Residence issued by their home tax authority. Depending on the treaty, the taxpayer may be entitled to either an exemption in Thailand or a credit for taxes already paid abroad.

Applying these provisions requires a careful reading of the relevant Double Taxation Agreements, as the relief mechanism differs from one country to another. Professional assistance is advisable to ensure proper application and documentation.

Legal documentation and professional assistance for tax filing in Thailand 

Thai tax law can be complex, so professional advice is often necessary, especially for expatriates with diverse types of income. You must retain all relevant records, such as contracts, invoices, bank statements, and proof of money transfers, as tax authorities may request them at any time.

Engaging a tax lawyer or certified accountant ensures compliance with both the Revenue Code and applicable international treaties. Legal advisors can assist not only in the preparation and submission of returns but also in representing clients before the Revenue Department in case of audits or refund claims.

If you are a high-net-worth individual or a business owner, planning your taxes carefully helps you comply with the law and manage your finances effectively.

Conclusion

Filing taxes in Thailand takes care, accuracy, and staying up to date with the law. The Revenue Code explains what you need to do, how to report income, and what happens if you do not comply. Meeting deadlines, keeping records, and using deductions help you stay compliant. If you are an investor or business owner, seeking professional legal advice can be highly beneficial. Benoit & Partners can support you by reviewing your tax situation, preparing your returns, and working with the Thai Revenue Department.

For further clarification on how your residency status affects your tax obligations, consult our dedicated guide: Tax Residency in Thailand.

FAQ

Tax returns must be filed by March 31 of the following year for paper submissions or April 8 for online filings. A mid-year declaration, when applicable, must be submitted by September 30.

Any person residing in Thailand for at least 180 days in a calendar year or deriving income from Thai sources must file, in accordance with Section 41.

Non-compliance leads to interest charges, fines, and possible imprisonment for intentional evasion, as provided in Sections 37, 89 bis, and 90.

Yes, if you are a tax resident and the income is remitted to Thailand within the same calendar year, pursuant to Announcement 161/2566.t.

Yes. Foreign taxpayers may register with their passport and taxpayer identification number to access the Revenue Department’s portal.