Thailand Bonus Tax Calculator
How much tax will your bonus pay in Thailand? This calculator uses the correct marginal method — comparing your full-year tax with and without the bonus — to show the real tax on the bonus, its effective rate, and the top bracket it lands in, using 2026 rates.
Bonus Tax Results
Tax on Your Bonus
฿0
Effective Rate on Bonus
0%
Bonus After Tax
฿0
How the Bonus Tax Is Derived (Marginal Method)
- Annual salary (salary x 12)
- ฿0
- Bonus
- ฿0
- Annual tax — without bonus (Tax A)
- ฿0
- Annual tax — with bonus (Tax B)
- ฿0
- Tax on bonus = Tax B − Tax A
- ฿0
- Top bracket the bonus reaches
- 0%
A Note on Withholding in the Bonus Month
In the month the bonus is paid, your employer usually recomputes the annualized tax (per Paw 96/2543), so the withholding on that payslip looks unusually high and may exceed the ฿0 shown above. The figure above is the true annual net tax on the bonus. Any over-withholding is refunded when you file your PND 90/91 return.
How Much Tax on a Bonus in Thailand? The Answer Is "Marginal"
Every December and January, the same question comes up: "I got a bonus — how much tax will they take?" Many people assume a bonus has its own fixed "bonus tax rate," like a flat 5% or 10%. It does not. A bonus is Section 40(1) assessable income under the Revenue Code — exactly the same category as your salary — so it is added to your annual income and taxed at the progressive 0-35% rates.
The correct way to answer "how much tax on my bonus" is therefore the marginal method:
1) Compute your full-year tax without the bonus → Tax A
2) Compute your full-year tax with the bonus → Tax B
3) Tax on the bonus = Tax B − Tax A
The result is the bonus's true tax burden. And because the bonus stacks on top of a salary that is already being taxed, it is taxed at your top marginal bracket — it does not start again from the tax-free 0% or the first 5% band the way the first slice of your salary does. That is exactly why a bonus "feels" so heavily taxed.
Why a Bonus Is Taxed at Your Top Rate
Thailand's personal income tax is progressive. The first 150,000 THB of net income is exempt, and higher slices are taxed at rising rates:
| Net Income (THB) | Tax Rate |
|---|---|
| 0 – 150,000 | 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 – 5,000,000 | 30% |
| Over 5,000,000 | 35% |
Across the year your salary "climbs" this ladder. By bonus time, your net income may already sit in the 10%, 15%, or 20% band, so the bonus continues from wherever the salary reached — not from 0%. If your salary has pushed your net income into the 15% band, every baht of bonus starts at 15%, unless the bonus is large enough to push into the next band, in which case the excess is taxed at the higher rate.
To see your full-year tax base with every allowance, use the Thailand income tax calculator, and check your monthly net pay with the Thailand salary calculator.
Worked Examples
These examples use the basic deductions (100,000 expense + 60,000 personal allowance + 10,500 social security) and match the calculator above to the baht.
Example 1: 30,000/month salary + 30,000 bonus (5% band)
- Annual income (no bonus): 360,000 → net income 189,500 → Tax A = 1,974.95 THB
- With bonus: 390,000 → net income 219,500 → Tax B = 3,474.95 THB
- Tax on bonus = 3,474.95 − 1,974.95 = 1,500 THB
- Effective rate = 1,500 ÷ 30,000 = 5.00% (the whole bonus sits in the 5% band)
- Bonus after tax = 28,500 THB
Example 2: 45,000/month salary + 200,000 bonus (straddles 10%/15%)
- Annual income (no bonus): 540,000 → net income 369,500 → Tax A = 14,449.90 THB
- With bonus: 740,000 → net income 569,500 → Tax B = 37,924.85 THB
- Tax on bonus = 37,924.85 − 14,449.90 = 23,474.95 THB
- Effective rate = 23,474.95 ÷ 200,000 = 11.74% — below the 15% top band, because the first slice is still taxed at 10% before crossing into 15%
- Bonus after tax = 176,525.05 THB
Example 3: 120,000/month salary + 240,000 bonus + 200,000 extra deductions (25% band)
- Annual income (no bonus): 1,440,000, minus basic deductions + 200,000 extra → net income 1,069,500 → Tax A = 132,374.75 THB
- With bonus: 1,680,000 → net income 1,309,500 → Tax B = 192,374.75 THB
- Tax on bonus = 192,374.75 − 132,374.75 = 60,000 THB
- Effective rate = 60,000 ÷ 240,000 = 25.00% (the whole bonus sits in the 25% band)
- Bonus after tax = 180,000 THB
Notice how the higher the salary, the higher the top bracket — and the more of the bonus is taxed away. The 30,000-salary earner pays 5% on the bonus; the 120,000-salary earner pays 25%.
Withholding in the Bonus Month — Why It Looks So Heavy
Many people are shocked by the payslip in the month they receive a bonus, because the withholding tax spikes far above normal. The reason is the withholding method under Revenue Department Instruction Paw 96/2543 — when a lump sum like a bonus is paid, the employer adds it to the projected annual income, recomputes the full-year tax, and collects the outstanding difference in that month.
The amount withheld in the bonus month can therefore exceed the bonus's true annual tax, especially if the bonus is paid early in the year (the system may estimate conservatively). But this is only an advance payment, not lost money. When you file your PND 90 or PND 91 return after year-end, all tax is reconciled against your actual income, and any over-withholding comes back as a tax refund. The headline figure this tool shows (Tax B − Tax A) is the true annual net tax on the bonus — the number to plan around, not a single month's withholding.
Note: a bonus is not subject to additional social security. Section 33 contributions are based on regular wages only (max 875 THB/month in 2026), so a bonus is reduced by income tax alone.
How to Reduce the Tax on Your Bonus (Legally)
Because the bonus is taxed at your top bracket, every extra deduction saves tax at that same top rate — which is especially valuable for higher earners:
- Increase your provident fund (PVD): up to 15% of wages, deductible in full. Someone in the 20% band adding 50,000 THB saves 10,000 THB in tax.
- Buy SSF/RMF/Thai ESG before year-end: especially in a year with a large bonus that pushes you into a higher band — the deduction pulls your base back down.
- Life and health insurance: life insurance is deductible up to 100,000 THB, health insurance up to 25,000 THB (combined life cap 100,000).
- Charitable donations: general donations are deductible up to 10% of income after other deductions; certain education/sports donations count double.
- Time your bonus: a bonus paid in December is that year's income, while one paid in January falls in the next year — if this year is unusually high, shifting the bonus can spread the tax base (subject to company policy).
Enter your planned deductions in the "Extra Annual Deductions" field above to see how much the bonus tax falls.
Limitations and Good-to-Know Details
- This tool estimates from regular salary x 12 + bonus. If you have other income types (rent, dividends, freelance), use the income tax calculator that supports all categories.
- The basic deductions applied automatically are: 50% employment expense (max 100,000) + 60,000 personal allowance + social security based on salary (max 10,500/year). Add anything else in the "Extra Annual Deductions" field.
- The tax figure shown is the bonus's true annual burden — not the withholding on the bonus-month payslip, which is usually higher and later refunded.
- A bonus counts as income in the year it is paid (cash basis) and is filed on that year's return.
- Results are estimates for planning, based on the 2026 (tax year 2569) personal income tax rates. For complex cases, consult a tax professional.
Official Sources
FAQ
How much tax do I pay on a bonus in Thailand?
There is no separate "bonus tax rate" in Thailand. A bonus is Section 40(1) assessable income — the same category as your salary — so it is added to your annual income and taxed at the progressive 0-35% rates. The real tax on the bonus equals your full-year tax WITH the bonus minus your full-year tax WITHOUT it. In practice this means the bonus is taxed at your TOP marginal bracket, because it stacks on top of the salary you already earn. Someone whose salary already sits in the 10% band starts paying 10% on the bonus; a large bonus that pushes you into the next band pays the higher rate on the portion above the threshold.
Is a bonus taxed separately from salary in Thailand?
No. Your bonus is combined with your salary and all other Section 40(1) income for the whole year, then taxed as a single amount using the progressive brackets. There is no flat withholding rate applied only to the bonus. This is the most common misconception — people assume the bonus is docked at a fixed rate, but it is simply added to your existing tax base and therefore taxed at your top marginal rate. That is why this tool uses the marginal method: it compares your annual tax in two scenarios to isolate the tax the bonus alone bears.
Why is so much tax taken from my bonus?
Because the bonus stacks on top of income that is already being taxed, it starts from your highest bracket, not from the tax-free first 150,000 THB or the initial 5% band. If your salary has already pushed your net income into the 20% bracket, every baht of bonus is taxed at 20% from the first baht. On top of that, in the month the bonus is paid, employers usually recompute the annualized withholding and collect the difference that month, so your payslip that month looks unusually heavy — but that is an advance payment, not a special penalty.
How much tax is withheld at source on a Thai bonus?
In practice the employer adds the bonus to the projected annual income in the month it is paid, recomputes the full-year tax, and withholds the difference that month (following Revenue Department Instruction Paw 96/2543). There is no fixed rate such as 3% or 5%. The amount withheld in the bonus month is therefore usually much higher than usual and can even exceed the bonus's true annual tax. Any over-withholding is refunded when you file your PND 90/91 return. The headline figure in this tool is the true annual marginal tax on the bonus — the real net tax burden.
How is the effective tax rate on a bonus calculated?
The effective rate on the bonus = bonus tax ÷ bonus amount × 100. If the whole bonus sits inside one tax bracket, the effective rate equals that bracket's rate exactly — for example, a 30,000 THB bonus for someone in the 5% band pays 1,500 THB = 5%. But if a large bonus straddles two brackets (say it pushes you from the 10% band into the 15% band), the effective rate lands between the two — a 200,000 THB bonus straddling 10%/15% might pay about 11.7%, which is lower than the 15% top bracket.
Are social security contributions deducted from a bonus?
No. Section 33 social security contributions are calculated on regular wages only (max wage base 17,500 THB/month = max 875 THB/month from 2026). Bonuses, attendance pay, overtime, and other non-wage income are not subject to additional social security. So a bonus is only reduced by income tax, not by social security.
How can I reduce the tax on my bonus?
Because the bonus is taxed at your top bracket, buying extra allowances saves tax at that same top rate. Effective moves include: increasing your provident fund contribution (up to 15% of wages); buying SSF/RMF/Thai ESG funds before year-end; life and health insurance; and charitable donations. Every extra baht of deduction lowers your tax base, cutting the bonus tax at your marginal rate — someone in the 20% band who adds 10,000 THB of deductions saves 2,000 THB in tax.
I received a year-end bonus — how do I file for it?
A bonus counts as income in the tax year it is paid. A bonus paid in December 2026 is 2026 income, filed on your PND 90/91 return by March 2027 (early April for online filing). A bonus paid in January 2027 is 2027 income instead. Your employer issues a withholding tax certificate (form 50 Bis) that already includes the bonus — use those figures when you file. If too much was withheld at source, you receive a tax refund.