Calculation method
How take-home pay is calculated and rounded
We publish the inputs, order of operations, rounding, and uncertainty behind the estimate.
Assumptions
The standard case uses the 2026 rules, Tokyo 23 wards, and an employee. Salary income, employee insurance, deductions, income tax, reconstruction tax, and resident tax are applied in that order.
Rounding
Intermediate amounts are truncated below one yen where the relevant rule requires it; displayed amounts are integer yen. Standard remuneration, prefectural insurance rates, and bonuses vary by input.
Accuracy and limits
This is an educational estimate. Employer payslips, municipal notices, and the insurer’s decision take priority.
2026 tax rules
Income tax uses the 2026 basic deduction, employment-income deduction, and reconstruction tax. Resident tax is estimated separately from prior-year income.
Insurance rates and standard remuneration
Employees use prefectural health insurance, the 18.3% employees’ pension rate split between employer and employee, employment insurance, and child/family support. Payslips and the insurer’s standard-remuneration grade take priority in real cases.
Bonus algorithm
A bonus is reduced by health, care, employees’ pension, employment insurance, and support contributions; the 2026 withholding rate then uses the previous salary after insurance and dependents. Year-end adjustment reconciles the final tax.
Worked example
For JPY 5m annual income in Tokyo at age 30 with no dependents, employment-income deduction, insurance, and deductions are applied in order, then income and resident tax are calculated to reach annual take-home pay. See the JPY 5m page for the exact figures.
Updates and corrections
Each page shows the rule version and last-checked date. System changes and data corrections are recorded in the update history; report an issue with its official source and reproducible inputs.
Rule registry and sources
Rule version: 2026.1. Rules checked: 31 August 2026 · Calculator logic updated: 4 September 2026 · Page updated: 4 September 2026.
Frequently asked questions
Why does this differ from a payslip?
Standard remuneration, bonuses, prior-year resident tax, and local per-capita levies can differ.
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