PND 90 and PND 91 in Thailand: A Practical Guide to Personal Income Tax Filing

Each year, individuals with assessable income subject to Thai personal income tax may be required to file a personal income tax return with the Revenue Department. For most people, this means either Form PND 91 or Form PND 90. Understanding which form applies to you, what deductions and allowances you can claim, and when to file can make the process considerably more straightforward.

Who Is Required to File

Filing obligations depend on your income, residency status, and circumstances.

Under Thai domestic tax law, an individual who stays in Thailand for 180 days or more in a calendar tax year is generally considered a Thai tax resident. Tax treaty residence can be determined differently where a Double Tax Agreement applies. Non-residents may also have Thai personal income tax filing obligations where they earn Thai-source income.

The filing thresholds for the 2025 tax year are:

• Single individuals: income exceeding THB 120,000 from employment, or THB 60,000 from other sources

• Married individuals: combined income exceeding THB 220,000 from employment, or THB 120,000 from other sources

Even if no tax is due, a return may still be required once these thresholds are crossed.

PND 91 or PND 90: Which Form Applies to You

The distinction between the two forms comes down to the nature of your income.

PND 91 is for individuals whose only income is from employment under Section 40(1) of the Revenue Code. This covers salaries, wages, allowances, and other compensation from an employer, including withholding tax already deducted.

PND 90 covers everyone else. If you receive income from a second source alongside your salary, such as freelance fees, rental income, dividends, or business income, PND 90 is the correct form. It is also the form used by individuals whose only income falls outside employment.

If you are uncertain which form applies to your situation, PND 90 is the more

comprehensive option and can accommodate employment income as well.

Filing Deadlines

For the 2025 tax year, the filing deadlines are:

• Paper submission: 31 March 2026

• Electronic filing (via the Revenue Department's e-Filing system or D-MyTax platform): 8 April 2026

Individuals earning income under Sections 40(5) to 40(8), which includes rental income, professional fees, and business income, are also required to file a mid-year return using Form PND 94. This covers income earned from January to June and must be submitted by 30 September of the same year. Tax paid on the mid-year return is credited against the final year-end calculation.

Key Deductions and Allowances

Thailand's personal income tax system allows for a range of deductions and allowances, which reduce your taxable income before applying the progressive tax rates.

Deduction / Allowance	Limit
Personal allowance	THB 60,000
Employment income deduction	50% of employment income, capped at THB 100,000
Spouse allowance	THB 60,000 (if spouse has no assessable income and relevant conditions are met)
Child allowance	THB 30,000 per qualifying child. Additional THB 30,000 for the second and subsequent qualifying legitimate children born on or after 1 January 2018, subject to applicable rules and limits
Parental allowance	THB 30,000 per parent, for parents aged 60 and above with income not exceeding THB 30,000, subject to qualifying conditions
Social Security contributions	Up to THB 9,000 (employees under Section 33 of the Social Security Act)
Life insurance premiums	Up to THB 100,000 for policies with a term of at least 10 years
Health insurance premiums	Up to THB 25,000. Combined with life insurance, total must not exceed THB 100,000
Annuity life insurance	Up to 15% of assessable income, capped at THB 200,000. Overall THB 500,000 annual limit applies across qualifying retirement contributions
Home loan interest	Up to THB 100,000 per year for qualifying residential mortgage loans

Other deductions and allowances may apply depending on individual circumstances, including donations to eligible organisations, investments in qualifying retirement funds, and certain government tax incentive programmes.

A Note on Foreign Income

From 1 January 2024, foreign-sourced assessable income earned by a person who is a Thai tax resident in the year the income arises may become subject to Thai personal income tax when that income is remitted to Thailand. This can apply where the income is remitted in the same year or in a later year.

The change was introduced through Revenue Department Departmental Instruction No. Por. 161/2566 and applies to foreign-sourced income earned from 1 January 2024 onwards. Foreign-sourced income earned before 1 January 2024 is generally outside the scope of this specific remittance-based rule.

Thailand currently has 61 effective double tax agreements and conventions. Where applicable, a Double Tax Agreement and Thailand's foreign tax credit rules may allow foreign tax paid to be credited against Thai tax liability, subject to the relevant conditions and limitations.

If you are a tax resident with foreign income, it is worth reviewing your situation early in the year to avoid unexpected tax obligations at filing time.

Penalties for Late Filing

Missing the filing deadline carries financial consequences. Where additional tax is payable, a surcharge of 1.5% per month or part of a month may apply from the due date until payment is made. A civil fine may also apply under the Revenue Code.

Where the tax payable exceeds THB 3,000, taxpayers may apply to pay the amount in up to three instalment, subject to the applicable conditions and Revenue Department procedures.

If you discover an error after filing, you should generally correct the return promptly. Depending on the circumstances, an amended return may result in additional tax and applicable surcharges or penalties.

How KLAY Can Help

Personal income tax in Thailand can involve more complexity than it appears, particularly for expatriates, business owners, and individuals with income from multiple sources or from overseas or navigating their company setup in Thailand.

KLAY supports individuals and companies with personal income tax filing, including assessment of which deductions and allowances apply, preparation and submission of PND 90 and PND 91 returns, and guidance on the treatment of foreign income. We work with individuals who want to ensure their filings are complete and accurate, without having to navigate the Revenue Department's processes alone.