Why Is Your Bonus Take-Home So Small? Japan Bonus Tax Explained
There is a clear reason why your net bonus is smaller than the gross figure. This guide breaks down the social insurance premiums (health, pension, employment) and the bonus-specific income tax rules, with a rough gross-to-net guide.
You finally get your bonus, then look at the payslip and the take-home amount is noticeably smaller than the gross figure. This is very common. In Japan, a bonus (shoyo) has social insurance premiums and income tax withheld under slightly different rules than your monthly salary. This article explains why the net bonus is lower than the gross amount, broken down into social insurance (health insurance, employees' pension, employment insurance) and the income tax withholding mechanism for bonuses.
The four deductions taken from a bonus
For company employees, four main items are deducted from a bonus:
- Health insurance (plus nursing-care insurance if you are 40 or older)
- Employees' pension insurance
- Employment insurance
- Income tax (withholding)
A key point: resident tax is NOT withheld from bonuses. Resident tax is based on the previous year's income and is split into 12 monthly deductions from salary, so it is not added to bonuses. Because of this, the net rate of a bonus tends to be slightly higher than that of monthly pay. To check actual figures, enter your gross amount in the bonus take-home calculator.
How social insurance works
Social insurance is the biggest reason your net bonus shrinks. The premium is calculated on the "standard bonus amount" (gross bonus rounded down to the nearest 1,000 yen) multiplied by each rate. Employer and employee split the cost (except employment insurance), so your payslip shows only your share.
Health insurance
The rate varies by health insurance society or prefecture, but is roughly 10% of the standard bonus amount (about 5% for the employee after the employer split). People aged 40 to 64 also pay nursing-care insurance on top.
Employees' pension
The pension rate is fixed at 18.3%, split evenly, so the employee share is 9.15%. This is usually the largest single deduction.
Employment insurance
Employment insurance is calculated on the bonus amount itself, with an employee share of roughly 0.5–0.6% for general businesses — small compared with the other two.
As a rough guide, the employee's social insurance burden often totals around 15% of the gross bonus.
Income tax withholding on bonuses
Bonus income tax is calculated differently from monthly salary:
- Take your previous month's salary minus social insurance.
- Combined with the number of dependents, look up the bonus tax rate on the official rate table.
- Apply that rate to the bonus minus social insurance.
So the bonus tax rate is determined by your previous month's pay and dependents. This withholding is only a provisional prepayment; it is reconciled in the year-end adjustment or tax return, and you may get a refund. For a full-year view, try the take-home pay calculator.
Gross vs. net: a rough guide
As a general guide, the net bonus is often about 75–85% of the gross (roughly 15% social insurance plus a few percent income tax), varying with age, dependents, previous salary, and insurance rates.
| Gross bonus | Approx. net (~80%) |
|---|---|
| ¥200,000 | ~¥160,000 |
| ¥500,000 | ~¥400,000 |
| ¥1,000,000 | ~¥800,000 |
For your own conditions, use the bonus take-home calculator.
Key takeaways
- Resident tax is not deducted from bonuses, so the net rate is higher than monthly pay.
- Pension (9.15%) and health insurance make up most of the deductions.
- Bonus income tax depends on previous-month salary and dependents.
- Withholding is a prepayment, reconciled at year-end.
Note: This is general information. Rates and methods change by year, region, and insurance society, and the figures are estimates. For exact amounts and personal advice, consult your payroll department, local government, official sources (Japan Pension Service, Japan Health Insurance Association, National Tax Agency), or a licensed tax/labor professional.
FAQ
Roughly what percentage of a bonus do I take home?
Generally about 75–85% of the gross. Social insurance is around 15% and income tax a few percent, varying with age, dependents, previous salary, and insurance rates.
Why is no resident tax deducted from bonuses?
Resident tax is based on the previous year and split into 12 monthly salary deductions, so it is not added to bonuses. This makes the bonus net rate higher than monthly pay.
How is bonus income tax determined?
It is based on your previous month's salary (after social insurance) and number of dependents, used to find a rate on the official table, then applied to the bonus minus social insurance.
Can the income tax withheld from my bonus be refunded?
Yes. Bonus withholding is a provisional prepayment, reconciled in the year-end adjustment or tax return, so over-withheld amounts may be refunded.
What is the employees' pension rate?
The pension rate is fixed at 18.3%, split with the employer, so the employee pays 9.15% — usually the largest single deduction from a bonus.