Social insurance (employee share)

Social insurance (社会保険) is the largest single thing that comes out of most Japanese salaries, and it is not a flat percentage of your pay. It is levied on the standard-monthly-remuneration grade (標準報酬月額) your salary maps to — a fixed step, not your exact wage — and, for most components, the employee pays only half (労使折半). These are the FY2026 (Reiwa 8, from the March-2026 payroll) rates; Includes the NEW FY2026 child-care support levy (from the April-2026 payroll).

The grade, not the salary

Health and nursing-care insurance read off a 50-grade table that tops out at a standard remuneration of ¥1,390,000; the employees’ pension reads off a separate 32-grade table capped at ¥650,000. The pension table truncates at both ends — pay below its floor collapses to the first grade and pay above its cap collapses to the last — so it is not a one-to-one slice of the health table. This is why someone who doubles their salary can watch their pension contribution stop growing: they have hit the grade ceiling. When that happens, the calculator says so on the line itself rather than letting the number quietly flatten.

What makes up the employee share (Tokyo default)

In Tokyo — the default prefecture — the components of the employee half are:

• Health insurance — 4.925% (the employee half of the 9.85% Tokyo total; the total varies by prefecture, see below), split 折半.
• Employees’ pension — 9.15% (half of the 18.300% total, fixed since September 2017), split 折半.
• Nursing-care insurance — 0.810% (half of 1.62%), added only for the second-category insured, ages 40–64.
• Child-care support levy — 0.115% (half of 0.23%), the new FY2026 charge, split 折半 on the same grade base.
• Employment insurance — 0.50%, charged on your actual total wages (no grade, no ceiling), not on the standard-remuneration grade.

Workers’ compensation (労災保険) is paid entirely by the employer — the employee share is ¥0 — so it is informational only and never part of your take-home. The full 折半 breakdown, grade by grade, is in the table below.

The new FY2026 child-care support levy

The child-care support levy (子ども・子育て支援金) is genuinely new for FY2026, collected from the April-2026 payroll onward, and it is split 折半 like the other components. A calculator that still omits it is now understating social insurance, which is why it is included and called out here.

Prefecture differences

The health-insurance rate is set per prefecture by Kyōkai Kenpo, so the same salary produces a different health premium in different prefectures. This tool defaults to Tokyo and lets you change it. It does not name a single “cheapest” prefecture: two readings of the full table disagreed on the lowest, so that remains an open item and stating it would be a guess.

The annual gross is treated as twelve equal months (standard remuneration = annual ÷ 12), and bonuses (賞与), which have their own social-insurance treatment, are not modelled separately in this version — a bonus-heavy pay mix will differ. No figure here carries the reviewer’s sign-off.