The short version
- Japan's public pension is built in two layers: kokumin nenkin (national pension) is the base floor everyone aged 20–59 is enrolled in, and kosei nenkin (employees' pension) sits on top of it for people hired by a company.
- You don't pick one — your employment type decides it automatically. A full-time hire at a qualifying company is enrolled in kosei nenkin (which folds in kokumin nenkin coverage); everyone else pays into kokumin nenkin directly.
- Kokumin nenkin is a flat amount regardless of income (¥17,920/month for fiscal 2026). Kosei nenkin is a percentage of your standard monthly remuneration (18.3%, split evenly with your employer, so about 9.15% comes out of your own pay).
- This is about pension enrollment while you're working in Japan — a different question from the lump-sum withdrawal payment you can claim after you leave the pension system for good.
Before moving to Japan, "kokumin nenkin" (national pension) is often the only term that comes up in pre-departure research. Then a first payslip arrives with a line reading "厚生年金保険料" (kosei nenkin hoken-ryo, employees' pension insurance premium), and the two names don't obviously connect. Nothing was mis-enrolled. They're two layers of the same public pension system, and which one applies to you was decided the moment your employment type was set, not by any form you filled out.
Japan's pension system in one picture: two floors, not two choices
Japan's public pension is commonly described as a two-story building. The ground floor is kokumin nenkin (国民年金), the National Pension: every resident of Japan aged 20 to 59, Japanese or not, is required to be enrolled in it, regardless of employment status. The second floor is kosei nenkin (厚生年金), the Employees' Pension. It sits on top of the ground floor for people employed at a company that meets the size and hours thresholds for mandatory enrollment. Being enrolled in kosei nenkin doesn't replace kokumin nenkin coverage; it's built to include it, which is why a company employee only sees a single deduction line.
How the numbers actually differ
Beyond who's enrolled, the two layers are calculated in opposite ways: one flat, one proportional to income.
| Kokumin nenkin (national pension) | Kosei nenkin (employees' pension) | |
|---|---|---|
| Who's enrolled | Everyone in Japan aged 20–59 not otherwise covered by kosei nenkin, including the self-employed, freelancers, students, and part-timers below the enrollment threshold | Employees at a company that meets the size/hours threshold for mandatory shakai hoken enrollment |
| How the premium is set | Flat monthly amount regardless of income: ¥17,920/month for fiscal 2026 | 18.3% of your standard monthly remuneration (a bracketed approximation of your salary, not the exact yen figure) |
| Who pays | You pay the full amount yourself, directly to your municipal office or by bank transfer | Split 50/50 with your employer, so about 9.15% of standard monthly remuneration is what actually leaves your own pay |
| How you see it | A payment slip (納付書) or bank debit; there's no employer payroll involved, so it never appears as a payslip line | A single deduction line on your payslip, usually labeled 厚生年金保険料 |
| Future benefit shape | Flat and income-independent: a fixed base amount for a full 40-year contribution history | Income-linked on top of the base amount, so higher lifetime earnings generally mean a larger second-floor payout |
Why this isn't something you choose
A question that comes up often: can you opt for kokumin nenkin instead of kosei nenkin, since the flat monthly amount looks smaller than a percentage of salary? The short answer is no. Enrollment tracks your employment type by law, so it isn't a preference you register anywhere. If your job meets the threshold for mandatory shakai hoken, kosei nenkin enrollment happens as part of being hired, the same way it isn't optional to skip health insurance while keeping the paycheck. What actually matters here is understanding which system applies to your current situation and why the deduction on your payslip looks the way it does, rather than trying to pick the cheaper-looking option.
What changes if your job situation changes
Switching from company employment to freelance work, or the reverse, moves you between the two systems rather than adding one on top of the other. Leaving a company job means your kosei nenkin enrollment ends with it, and you're expected to switch to paying kokumin nenkin directly within 14 days — the same notification window that applies when switching health insurance coverage after quitting a job (covered in the related guide below). Taking a new company job later moves you back into kosei nenkin the same way it happened the first time: automatically, through the new employer's shakai hoken setup.
Where this guide stops
This page explains which pension system you're in while you're working in Japan and how the premium is calculated — it isn't the guide for what happens to that money after you leave the country for good. Claiming money back from the pension system you paid into is a separate process (the lump-sum withdrawal payment, linked below), with its own eligibility window and tax treatment. This page also doesn't cover individual benefit projections or advice on retirement planning — for those, the Japan Pension Service and its local offices (nenkin jimusho) are the correct starting point.
Related reading
- How to read a Japanese payslip (kyuyo meisai) — where the 厚生年金保険料 deduction sits among the other lines.
- The lump-sum withdrawal payment: getting some of your Japanese pension back — the separate process for after you leave the pension system.
- Health insurance after you quit your job in Japan — the parallel switch that happens to your health coverage on the same kind of timeline.
Sources
Confirmed via search engine results on 2026-09-03 (this environment's direct fetch of nenkin.go.jp returns a 403, consistent with prior guides on this site; figures are cross-checked across the sources below):
- Japan Pension Service (nenkin.go.jp), summarized via search results — the two-tier structure (kokumin nenkin as the base layer, kosei nenkin as the employee layer built on top of it) and the 20–59 mandatory enrollment age range for kokumin nenkin.
- Japan Pension Service (nenkin.go.jp) — 会社を退職したときの国民年金の手続き ("National pension procedures when you leave a company") — the 14-day notification deadline for switching to kokumin nenkin after leaving kosei nenkin coverage, cross-checked against a second summary (moneiro.jp).
- Ministry of Health, Labour and Welfare / 社労士ナビ summary of the fiscal 2026 (令和8年度) figures — kosei nenkin held at 18.3% (split 50/50 employer/employee) and the kokumin nenkin flat monthly premium of ¥17,920 for fiscal 2026, cross-checked against a second social-insurance-office summary (まき社会保険労務士事務所).
- GaijinPot — Understanding the Japanese Pension System Part 1/3 — the employee-vs-everyone-else enrollment split and the automatic (non-optional) nature of kosei nenkin enrollment for qualifying jobs.
- Japan Living Life — Japan Pension System for Foreigners: Complete Guide — the income-linked benefit structure for kosei nenkin versus the flat benefit for kokumin nenkin, and the link between leaving a company job and switching pension systems.