1. Start with net taxable income
For the ordinary net-income method, identify assessable income, deduct the expenses allowed for its category, then apply eligible allowances and exemptions before calculating tax.
Net taxable income = included income − allowable expenses − eligible allowances and exemptions.
Section 40(1) and 40(2) income qualifies for a 50% expense deduction, capped at THB 100,000 in aggregate. The THB 60,000 personal allowance is separate. Other income categories have their own rules. Revenue Department rules
2. Apply each rate to its own band
The first THB 150,000 of net taxable income is exempt. Moving into a higher band does not apply that higher rate to all income. Rate schedule · First-band exemption
| Annual net taxable income (THB) | Marginal rate |
|---|---|
| Up to 150,000 | Exempt |
| Over 150,000 to 300,000 | 5% |
| Over 300,000 to 500,000 | 10% |
| Over 500,000 to 750,000 | 15% |
| Over 750,000 to 1,000,000 | 20% |
| Over 1,000,000 to 2,000,000 | 25% |
| Over 2,000,000 to 5,000,000 | 30% |
| Over 5,000,000 | 35% |
Other income types or special cases may require additional calculation methods. This table alone does not determine every taxpayer’s final liability.
3. Check eligibility and shared limits
| Item | Amount and conditions |
|---|---|
| Personal allowance | THB 60,000. |
| Spouse without income | THB 60,000, subject to marital-status and claim conditions. |
| Own health insurance | Actual eligible premiums up to THB 25,000, within the combined THB 100,000 life-insurance/life-savings cap. |
| Own life insurance | Actual eligible premiums within the THB 100,000 limit; policy conditions include at least ten years of coverage and an insurer in Thailand. |
Personal and spouse allowances · Health insurance cap · Life insurance conditions
This is not a complete annual deductions list. Children, parents, retirement savings, donations and temporary measures need separate eligibility and tax-year checks. A receipt alone does not make an expense deductible.
4. Build the annual calculation from records
- Identify the tax year and classify actual income.
- Keep expense deductions separate from personal allowances.
- For each allowance, check eligibility, actual payment, evidence and individual limits.
- Apply shared caps before adding the eligible amounts.
- Calculate tax separately for each net-income band.
- Apply eligible withholding and other tax credits when determining payment or refund.
Withholding is a tax credit, not an income allowance. PND91 tax-year 2025 calculation guide
5. Zero tax can still mean a filing obligation
Filing thresholds differ from the threshold at which net income becomes taxable. For example, a single person with employment income alone exceeding THB 120,000 per year meets the filing threshold even if eligible deductions leave no tax payable. Filing thresholds
Sources were checked on 8 October 2026. This article explains basic rules and does not claim to cover every special measure for tax year 2026. Check the relevant filing year and individual circumstances before filing. BFF can help review your income records and allowance evidence.
Official sources
- กรมสรรพากร — บัญชีอัตราภาษีเงินได้ / Personal income tax rate schedule
- กรมสรรพากร — โครงสร้างค่าใช้จ่าย ค่าลดหย่อน และเกณฑ์ยื่นแบบ / Expenses, allowances and filing thresholds
- กรมสรรพากร — Clear Cut เกร็ดลดหย่อน / Health insurance allowance conditions
- กรมสรรพากร — ค่าลดหย่อนประกันชีวิต / Life insurance conditions
- คู่มือ ภ.ง.ด.91 ปีภาษี 2568 — ใช้ประกอบการอธิบายหลักการ ไม่ใช่คู่มือสิทธิพิเศษปี 2569 / PND91 tax-year 2025 guide
This is a general explanation. Application depends on the facts and the rules for the relevant period.