Everyone celebrates the tiny first NHI bill. Mio doesn't — Mio knows it's tiny because the system is looking at a year when you hadn't earned in Japan yet. The next year it catches up. Here's exactly how the premium is built, so the jump never surprises you.
National Health Insurance (kokumin kenkō hoken) is the public health insurance run by your city or ward for people not covered by employer insurance (shakai hoken) — freelancers, the self-employed, many students, people between jobs, and others. If you have a residence status of roughly 3 months or more and aren't on employer insurance, you're generally required to enrol at your city office. The premium is billed to the household (the head of household receives it), covering everyone in the household who's on NHI.
Your annual premium is the sum of up to three components, each set by your municipality:
• Income levy (shotoku-wari) — the big one. Based on your previous calendar year's income, minus a basic deduction (commonly ¥430,000), multiplied by the city's income rate.
• Per-capita levy (kintō-wari) — a flat amount for each enrolled person in the household.
• Per-household levy (heitō-wari) — a flat amount per household (some municipalities use this, others don't).
To make it more layered, each of those is calculated separately for three portions: the medical portion, the elderly-support portion, and — only for ages 40–64 — the long-term care portion (kaigo). You add them all up to get the yearly premium.
The income levy is the largest slice, and it's based on what you earned last calendar year. If you arrived in Japan mid-year, your previous-year Japanese income was ¥0 (or nearly so), so the income levy is ¥0. What's left is just the flat per-person and per-household parts — and low- or no-income households usually qualify for a statutory reduction (commonly 7 / 5 / 2 tenths off the flat parts). Net result: a very small first bill. It feels like NHI is cheap. It isn't — it's just delayed.
By your second year, the system finally has a full calendar year of your Japanese income to look at. The income levy switches on, calculated on that whole year's earnings — and any low-income reduction you had in year 1 may no longer apply. So the premium can multiply even though nothing about your health or your household changed. This is the same one-year-lag logic behind Japan's resident tax (juminzei) year-2 shock → — both look backward, both catch newcomers.
There's a ceiling. Nationally, the combined maximum for FY2025 (令和7年度) is ¥1,090,000 per household — split as roughly ¥660,000 (medical) + ¥260,000 (elderly-support) + ¥170,000 (long-term care). These caps are raised most years by government ordinance (they've climbed steadily; a further increase is scheduled for later years), so check the current figure for your fiscal year. High earners hit the cap and pay no more above it — but for most newcomers the cap isn't the issue; the year-2 income levy is.
NHI is municipal. Each city and ward sets its own income rates, per-person amounts, whether it charges a per-household levy, and its exact caps — and updates them yearly. So the same income can produce meaningfully different premiums in Tokyo vs Osaka vs a rural town. Any specific number you see online (including this page's ¥430,000 deduction and the example rates below) is illustrative — only your own city office is authoritative for your bill.
| Your situation | Year-1 NHI | What to plan for |
|---|---|---|
| Just arrived, ¥0 Japan income last year, on NHI | Tiny (often reduced flat parts only) | Save for the year-2 income levy — don't spend the gap |
| Freelancer/self-employed, income rising | Low → then climbs | Each raise shows on next year's bill |
| Student with little/no income | Often heavily reduced | Ask about low-income reduction & student status |
| Left a job, moved employer → NHI | Based on last year's salary — can be high | Compare with continuing employer insurance → |
| Aged 40–64 | Add the long-term care portion | Bill is structurally higher than under-40s |
| Very high earner | Rises to the ~¥1.09M cap | Cap limits the top, but it's a big number |
Illustrative only. Rates, deductions, reductions, per-household levy and caps differ by municipality and fiscal year — confirm with your city/ward office.
Budget the jump: treat year 1's low bill as temporary and set money aside for year 2, when the income levy kicks in on a full year of earnings. Check for reductions: if your income was low, ask your city office about the statutory low-income reduction — it can cut the flat parts sharply. Compare when changing jobs: leaving employer insurance for NHI can be pricey in year 1 because it's still on last year's salary; sometimes continuing your old employer's plan (nin-i keizoku) is cheaper — see the job-change health insurance gap guide →. Keep your address current so bills and reduction notices actually reach you.
Related reading: Health insurance in Japan for foreigners →, the resident-tax year-2 shock →, and long-term care insurance (kaigo hoken) →.
Mio