Look at the tax impact of the bonus before and after it's received.
According to the 2026 tax return.
Bonus Tax Impact Calculator
The Bonus Tax Impact Calculator estimates an income, tax or statutory-cost estimate for the figures entered from the income, employment or business status, relevant period, allowances and current thresholds shown on the page. Replace the example values with your own bonus tax impact figures and recalculate after changing an assumption. Treat it as a planning estimate and independently verify the current rule or provider terms.
Calculate how much the bonus would increase your taxable income for the year, and compare the two tax deductions at the point of payment.
Calculated from average salary + average monthly bonus.
Method B (total calculation)
Bonus withholding tax
-
Calculated from total income and subtracting normal salary.
How to calculate bonus withholding tax
Method A (recommended by the Revenue Department for large bonuses)
Calculate average monthly bonus = bonus ÷ number of months worked
Plus an average bonus plus normal salary.
Calculate annual tax on total income (income × 12 − expenses − deductions).
Calculate annual tax from regular salary. (not including bonus)
Bonus tax = (total annual tax − annual tax excluding bonus) × number of months worked
Frequently asked questions
How are bonuses taxed?
Bonus is income type 40(1) and must be included with salary when submitting the form at the end of the year. But when withholding tax, employers can choose to use Method A (calculated separately from normal salary) or Method B (calculated together).
What is Method A?
Method A is to separate the bonus tax calculation from the regular salary. By dividing the bonus by the number of months worked in that year. Then add it to the average salary. Calculate monthly tax Then multiply back by the number of months worked.
Which method pays less tax?
Depends on the situation Method A is generally less taxable for larger bonuses that make it jump to a higher tax bracket. This calculator compares both methods.
What method will employers use to deduct bonus tax?
Employers often use Method A as the default. Because it often results in lower withholding taxes. However, no matter which method is used The actual tax payable throughout the year will be the same. Because at the end of the year we still have to calculate the total.
How do bonuses affect year-end tax planning?
The bonus received this year will be included in the full year's income, resulting in a higher net income. You should plan to buy more SSF/RMF if you get a higher bonus than normal. To reduce taxes that will increase
The calculated results are estimates for tax or expense planning. Before actually submitting, you should check the latest rates and conditions from the official agency.
Calculated based on the information you enter and the rate specified on the tool page.
Special cases may require additional evidence or conditions.
The final numbers may change according to actual documents and government agency announcements.
Disclaimer: Calculation results are only estimates. Refer to the Revenue Department regulations for the year 2026. Please consult a tax expert for specific cases.
English calculator guide
How to use the Bonus Tax Impact Calculator
Use this page to test a specific bonus tax impact scenario. Enter your own values in the calculator above, review the units beside each field, and recalculate after changing an assumption. The result updates the bonus tax impact estimate instead of relying on a generic example.
Build a baseline bonus tax impact case with figures that match your situation.
Run a second bonus tax impact case after changing the rate, period, quantity or other key assumption.
Record the difference between the two bonus tax impact results and the input responsible for it.
Inputs for the bonus tax impact estimate
For this bonus tax impact calculation, check the income, employment or business status, relevant period, allowances and current thresholds shown on the page. The result is designed to show an income, tax or statutory-cost estimate for the figures entered, not a guaranteed provider price or official decision.
How the bonus tax impact result is calculated
The calculator applies the displayed statutory rates, thresholds and allowances to the figures you enter. Reusing the same bonus tax impact inputs will produce the same estimate, which makes the page suitable for controlled scenario comparisons.
Checks for a bonus tax impact decision
Check the effective date and confirm current rules with the relevant Thai authority or a qualified adviser. For bonus tax impact, Treat the result as an estimate for planning. Tax rules, eligibility and deduction limits can depend on the tax year and your evidence, so compare the result with current Revenue Department guidance or a qualified adviser. Because this calculation can affect an important financial, legal or health decision, independently verify the inputs and current rules before relying on the result.
Language QA
Terminology, numeric values and calculator controls checked
Review formula structure, test cases, data sources, effective dates, and risk language accordingly.How to check our · There is no claim that an outside professional reviewed it. Unless the page directly states the name and qualifications. This content is therefore not individual advice.
This history and results reside only in this device's browser. Press clear to delete immediately.
💾 Saved calculations
Save numbers only in this device's browser. It could be health or financial information. Therefore, the entered values or results are not sent to the server. You can delete them all from the button above. And data should be cleared when sharing the device with others.
Select 2–5. Items to compare
📊
There are no saved calculations yet.
Press the "Save" button after calculation to store the results.
