Japan Worker Tax Calculators 2026 — Nenmatsu-Chousei, Zangyou-Dai, Ikuji-Kyuugyou

Working in Japan means dealing with nenmatsu-chousei (year-end tax adjustment), zangyou-dai (overtime pay), and — if you're starting a family — ikuji-kyuugyou-kyufukin (childcare leave benefits). Most people calculate these by hand or wait for HR to tell them, which often produces surprises.

I built 3 free Japanese-language calculators that run entirely in your browser. No signup, no tracking, no data leaves your device. They're in Japanese with a clean mobile-first UI.

1. Nenmatsu-Chousei Keisan (Year-End Tax Adjustment)

Every December, Japanese employers process the year-end tax adjustment to reconcile the tax withheld during the year against your actual tax owed. You either get a refund or pay extra — but most workers only find out after it happens.

This calculator asks for your annual gross salary, social insurance premiums, life insurance deduction, earthquake insurance deduction, spousal/dependent info, and tax already withheld. It returns either your expected refund (還付金) or additional payment (追加納税) using the 2026 Japanese income tax brackets and employment income deduction (給与所得控除) formula.

Try it: 年末調整計算ツール

2. Zangyou-Dai Keisan (Overtime Pay Calculator)

Japanese labor law (労働基準法) mandates specific overtime premiums: 1.25x for normal OT, 1.50x for OT over 60 hours per month, +0.25 additive for late-night work (22:00-05:00), and 1.35x for statutory holiday work. These stack — late-night overtime is 1.50x, late-night holiday is 1.60x.

The calculator separates each bucket (regular OT, 60h+, late-night, holiday) and computes the per-hour base wage from your base salary and scheduled monthly hours. Useful for checking whether your paystub is correct or if you're owed unpaid overtime.

Try it: 残業代計算ツール

3. Ikuji-Kyuugyou-Kyufukin Keisan (Childcare Leave Benefits)

Japan's childcare leave benefit (育児休業給付金) is paid through employment insurance (雇用保険). The calculation is two-staged: the first 180 days pay 67% of your pre-leave daily wage, then 50% for days 181 onward. Both stages have monthly caps (¥315,369 for stage 1, ¥235,350 for stage 2 in 2026).

The calculator asks for your average monthly salary from the 6 months before your leave start date and your planned leave duration. It shows the total expected benefit plus a month-by-month breakdown — useful for financial planning during the leave period. It also covers the post-birth dad leave (産後パパ育休) which pays up to 28 days at 67%.

Try it: 育児休業給付金計算ツール

Why These 3 Tools Together

These three calculations hit different life stages of a Japanese worker: the end-of-year tax reconciliation (everyone), overtime pay disputes (salaried workers), and parental leave planning (new parents). Together with our existing tedori calculator and furusato nozei simulator, they cover the main financial questions a Japanese worker asks in any given year.

All tools are free forever, run in your browser, and never send your salary data to a server. Bookmark the Japan tools hub for the full set.

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Originally published at https://tool.teamzlab.com

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