Japan Bonus Tax Calculator 2025 (賞与の所得税)
On a ¥500,000 bonus with a ¥300,000 prior month salary, income tax withheld is approximately ¥30,000-45,000. Social insurance (health + pension) deducts another ~¥73,750, leaving net bonus of roughly ¥380,000-395,000.
Gross salary in the month before the bonus. Used to determine withholding rate.
Bonus Withholding Rate
20.4%
Income Tax Withheld
JPY99,750
Reconstruction Surcharge (2.1%)
JPY2,095
Social Insurance (approx)
JPY73,750
Net Bonus After Deductions
JPY3,24,405
Approximate calculation. The official method uses the NTA bonus withholding table based on prior month deductions. Actual withholding may differ slightly. Year-end adjustment (年末調整) corrects any over/under-withheld amounts.
What is the Japan Bonus Tax Calculator?
Bonus income (賞与, shōyo) in Japan is subject to income tax withholding using a special calculation that references the prior month's monthly salary withholding. Social insurance contributions (health insurance + welfare pension + employment insurance) also apply to bonus amounts. The year-end adjustment (年末調整) settles any difference between withheld and actual tax liability.
Formula
Bonus withholding rate is derived from prior month salary. Social insurance deducted at standard rates on bonus amount.- T_bonus
- = Tax withheld from bonus
- S_prior
- = Prior month taxable salary
- B
- = Bonus amount
How to use the Japan Bonus Tax Calculator
- 1
Step 1
Enter your bonus amount.
- 2
Step 2
Enter your prior month gross salary.
- 3
Step 3
Enter number of dependents.
- 4
Step 4
View withheld taxes and net bonus amount.
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Frequently asked questions
How is bonus tax calculated in Japan?
The NTA provides a bonus withholding table. The rate is determined from a table lookup based on: (prior month taxable salary − prior month withholding) and the number of dependents. The bonus is multiplied by this rate to get the withholding amount.
Is bonus income subject to social insurance in Japan?
Yes. Social insurance premiums apply to bonuses at the same rates as monthly salary — health insurance (~10% total, ~5% employee), welfare pension (18.3% total, 9.15% employee), and employment insurance (0.6%). Pension is capped at ¥1,500,000 per bonus payment.
Does the year-end adjustment correct bonus tax?
Yes. The year-end adjustment (年末調整, nenmatsu chosei) reconciles all withholding — including bonus withholding — against the actual annual tax liability. Most salaried employees receive a small refund in December.
Sources
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Calculated with CalcCrack