If you will live in Japan for three months or more as an international or exchange student, you are expected to join National Health Insurance (NHI, or "Kokuho") at your local municipal office. Once enrolled, you normally pay 30% of covered medical costs at the clinic or pharmacy, and a monthly cap protects you from very large bills. Here is what to do after arrival, what NHI covers, and where the gaps are.
Who has to join
NHI is the public health insurance for residents of Japan who are not covered by another public scheme. According to the Ministry of Health, Labour and Welfare (MHLW), anyone with an address in Japan becomes an NHI member unless they fall into an excluded group, such as:
- people already covered by employee health insurance, and their dependents;
- people receiving public assistance (welfare);
- people in the late-stage medical care system for the elderly;
- foreign nationals on short-term stays.
JASSO's Study in Japan guidance puts it simply for students: foreign residents staying in Japan for three months or more need to subscribe. A one-semester or full-year exchange usually falls into this group. Very short programs generally do not, so if your program is only a few weeks long, arrange private travel or student insurance before you leave home.
When and where to enroll
- Register your address first. After you move in, complete resident registration at the city or ward office.
- Join NHI at the same office. MHLW says you must submit the paperwork to your municipality's NHI counter within 14 days of becoming eligible. The same 14-day rule applies when you leave the system, for example when you move out of Japan.
- Check the local document list. Each municipality decides which documents it needs, so look at your ward's website or ask at the counter.
Many students arrive, stay somewhere temporary for a few weeks, and only then register. If you are in a furnished monthly rental while you look for longer-term housing, you can still register that address, which lets you start NHI right away instead of waiting until you move again.
How premiums work
Premiums are not a flat national fee. Each municipality sets the calculation method by local ordinance, and premiums are calculated per household based on a mix of a flat per-person portion and an income-based portion.
- Income declaration matters. Your premium is based on the previous year's income, including part-time work. Even if you had little or no income, declare it, because the municipality cannot apply reductions otherwise.
- Low-income reductions. For households below income thresholds set by law, the flat-rate portion is reduced by 70%, 50% or 20%. If you had little or no income in Japan the previous year, you may qualify once your declaration is filed.
- Hardship relief. If disaster or other special circumstances make it hard to pay, you may be able to get a reduction or a deferral. Ask your municipality's NHI counter.
What NHI covers
When you are sick or injured, show your NHI credentials at a medical institution and NHI pays 70% of the cost of covered care. You pay the remaining 30%. Covered care includes consultations, prescribed medicine, treatment and surgery, and hospital stays.
Care that falls outside the insurance system is a different story: Study in Japan reminds students that any medical costs not covered by insurance are paid entirely by the patient, so ask the clinic first if you are unsure.
The high-cost medical expense system
If your out-of-pocket medical costs exceed a monthly limit, the excess is refunded under the high-cost medical expense system. Limits depend on age and income. MHLW gives an example under the rules from August 2026: a person under 70 with an annual income of about 3.7 to 5.1 million yen who receives 1 million yen of treatment pays roughly 93,000 yen out of pocket. Most students earn far less, so their limits are lower.
Other features worth knowing:
- Multiple high-cost months: if you hit the limit in three or more of the past 12 months, the limit drops further from the fourth month.
- New annual cap: from August 2026 there is also a yearly ceiling (counted from August to the following July), which mainly helps people with long-term treatment.
- Avoid paying first: if you use a My Number Card registered as your health insurance card, or get a limit certificate in advance from your municipality, the hospital only charges up to your limit instead of you paying in full and claiming later.
Insurance NHI does not replace
NHI is medical insurance; it does not pay for damage to property or compensation when you injure someone else. Your school will tell you about extra plans, which commonly include:
- Gakkensai: personal accident insurance for students, covering injuries during classes and commuting. Most universities adopt it.
- Inbound Futai-Gakuso: a supplementary plan that tops up Gakkensai for international students.
- University CO-OP Kyosai: a mutual aid scheme you can join through your university co-op.
These can cover situations like a cooking fire in your apartment or injuring someone while cycling. Ask your host university which plans it recommends.
Quick checklist
- Staying three months or more: register your address, then join NHI within 14 days.
- Declare your income every year, even if it is zero.
- Pay premiums on time and keep the payment notices.
- Before a planned hospital stay, ask about the limit certificate.
- When you leave Japan, notify the NHI counter within 14 days.
Figures in this guide reflect official pages as of October 2026. Premium amounts and procedures vary by municipality, so always confirm with your local office.
Sources
- 厚生労働省「国民健康保険の加入・脱退について」(checked 2026-10-04)
- 厚生労働省「国民健康保険の保険料・保険税について」(checked 2026-10-04)
- 厚生労働省「高額療養費制度を利用される皆さまへ」(checked 2026-10-04)
- 日本学生支援機構（Study in Japan）「Insurance」(checked 2026-10-04)
This article was created by OHAYO Stay based on the sources above (edited, reorganized and translated). It is not an official publication. Facts are summarized in our own words; see the linked pages for the official details.
Rules and dates can change. Always confirm with the official source before you apply.