Your National Health Insurance Bill in Japan, Explained

If you are on National Health Insurance (国民健康保険, kokumin kenko hoken, often shortened to 国保 kokuho), your city or ward office bills you for it directly. That usually means an envelope in June with a notice and a stack of payment slips, a second batch later in the year, and possibly revised notices in between.

The notice is dense, the amount often changes from year to year, and it is addressed to whoever is registered as head of the household, which is not always the person who is insured. Here is how to make sense of it.

We use Nerima City in Tokyo as the running example, because its 2026 English NHI guidebook is unusually thorough. Every municipality runs its own NHI and sets its own rates, so your numbers and dates will differ. The structure is broadly the same everywhere.

Who gets the bill

NHI is organized by household. Premiums are calculated for the household as a unit, and Nerima's guide says the notice and payment slips "will be mailed to the head of household, as stipulated by law."

That leads to a common surprise. If your spouse is on NHI but you are on your employer's health insurance, and you are registered as head of household (世帯主), the NHI bill arrives in your name anyway. Nerima's guide explains that the head of household receives payment notices "even if the head of household is not enrolled in NHI," but only pays for the members who are.

When the notices come

In Nerima, as in many cities, the timing is:

Late June: the premium notice (納入通知書 or similar) for the fiscal year (April to March) and payment slips for June to October, plus one slip for paying the full year at once.
Late November: payment slips for November to March.

The year's premium is split into ten instalments from June to March. No payments fall due in April or May, because the city cannot calculate your premium until it has your previous year's income, which its tax section finalizes in mid-June. Yokohama uses the same ten-instalment schedule on its English premium page.

If you pay by automatic bank debit, you normally get only the notice, without slips.

Revised notices can arrive at any time. Someone joining or leaving the household's NHI, or a change in the income figures, triggers a recalculation. If you have overpaid, the city sends a refund notice for you to fill in and return. If you have underpaid, it sends new slips.

Why the amount changes (and often jumps in year two)

An NHI premium has two kinds of component:

An income-based amount (所得割), a percentage of the previous year's income of the household's NHI members.
A per-capita amount (均等割), a flat charge for each member.

Most cities stack several of these parts: a basic medical portion, a portion supporting the medical system for people 75 and over, and a long-term care portion for members aged 40 to 64. From fiscal 2026 there is also a new child and childcare support portion. For fiscal 2026, Nerima's basic medical portion is 7.51% of the members' income (after a ¥430,000 basic deduction) plus ¥47,600 per member. Other cities use different figures.

Because the income-based part looks at last year's Japanese income, many people pay mostly the flat part in their first year and see a much larger bill in their second year, after a full year of Japanese income. The same logic applies when a working year is followed by a year of lower income: the bill reflects the good year.

If you moved in from another city, your new city may bill you only the per-capita amounts at first. Nerima notes that it recalculates once it gets your income information, so a revised, higher notice can follow.

Reading the notice

Look for:

年度 (fiscal year), for example 令和8年度 (April 2026 to March 2027).
世帯主 (head of household) and the list of insured members (被保険者).
年間保険料 (annual premium), often broken down into 医療分 (medical), 後期高齢者支援金分 (elderly support), 介護分 (long-term care) and, from fiscal 2026, 子ども・子育て支援金分 (child and childcare support).
軽減 (reduction), if one was applied.
期別 and 納期限: each instalment's amount and due date. In Nerima each instalment is due at the end of its month.

Reductions you might qualify for

There are no student discounts, but there are several reductions:

Low-income reductions (70%, 50% or 20% off the per-capita amounts). In Nerima these are applied automatically, based on the household's declared income. The catch is that the city needs an income declaration for everyone concerned. Nerima's guide says that if the head of household or any member "has not filed a tax report," the household is not reviewed for reductions. Even if you had no income, file a resident tax declaration (住民税申告). If you lived outside Japan on January 1, Nerima sends a simplified income report to fill in instead.
Involuntary unemployment. If you lost your job because of bankruptcy, layoff or similar, and your employment insurance papers show a qualifying separation code, the income used to calculate your premium can be cut to 30% of your previous salary until the end of the following fiscal year. You have to apply.
Childbirth. Premiums are reduced for the months around a birth.
Special circumstances such as disaster or a sharp drop in income from illness or a death in the family. Ask your city.

The details, codes and deadlines vary, so check your own municipality's NHI page or counter (国保年金課 or similar).

What if you don't pay

Missing an instalment starts a sequence that is spelled out on Yokohama's page. First a reminder, then late payment charges calculated per day, then demands that warn of seizure, and eventually an investigation of your assets. That can lead to seizure of savings or salary under the National Tax Collection Act. Nerima adds that if premiums stay unpaid for a year or more, you may have to pay the full cost of treatment at the clinic and claim the insured portion back later.

For foreign residents there is one more reason not to let it slide. Yokohama states plainly that "if you are in arrears with your insurance premiums, you may not be allowed to renew your period of stay."

If you cannot pay, contact your city before the deadline. Nerima directs residents to its payment guidance center to discuss options.

Leaving NHI (new job, moving away, leaving Japan)

NHI does not stop by itself. If you join an employer's health insurance, you need to file a withdrawal at your city office within 14 days. Nerima warns that "you will continue to be billed for insurance premiums until you complete the withdrawal procedure."

If you are leaving Japan, file your moving-out notification (転出届) at the city office before you go. Nerima's guide says that if you skip it, you stay enrolled "and will be required to pay insurance premiums while you are overseas," and the city cannot backdate your withdrawal when you return. The city then recalculates the year's premium and may send a final bill for any balance, so Nerima asks people not to close their Japanese bank account while a refund might still be due.

One less envelope to decode

NHI mail is a steady stream of notices, slips, revisions and refund forms, all in Japanese and all addressed to the head of household. If you want a second pair of eyes, Jozu takes a photo of the letter, explains what it is and what it is asking you to do, and keeps track of the payment deadlines for you. For decisions about your own premium, your city's NHI counter is the authority, and many have interpreters or phone translation services.

Related: Understanding Japanese Health Insurance covers enrolling and what NHI pays for.