Short answer
This relates to the 高額療養費制度 (kōgaku ryōyōhi seido, High-Cost Medical Expense Benefit system). Within the same calendar month, if your 自己負担 (jiko futan, out-of-pocket share) at medical institutions exceeds your 自己負担限度額 (jiko futan gendogaku, self-pay cap), which is tiered by your income and age, you can apply to the 保険者 (hokensha, insurer) you are enrolled in — for National Health Insurance (国保, kokuho) this is your municipality; for employee insurance it is 協会けんぽ (Kyōkai Kenpo, Japan Health Insurance Association) or your company's 健保組合 (kenpo kumiai, health insurance society) — and have the excess refunded. Applying in advance for a 限度額適用認定証 (gendogaku tekiyō ninteishō, certificate of application of the cap) or using the マイナ保険証 (maina hokenshō, My Number card used as a health insurance card, via online eligibility confirmation) lets the hospital counter charge you only up to the cap on the spot, so you do not have to pay in full first and claim the refund later. Note: only the self-pay share of insurance-covered treatment counts toward the benefit — hospital meal charges, extra charges for private rooms (差額ベッド代, sagaku beddo dai), advanced medical treatment (先進医療, senshin iryō), and non-covered (private) treatment are not counted and must still be paid in full. For the exact cap amounts, what counts, time limits, and procedures, follow the explanations from the Ministry of Health, Labour and Welfare and your insurer.
What this document is
Around the High-Cost Medical Expense Benefit, you may come across these documents and terms:
- 高額療養費制度 — the system under which, when your self-pay in the same month exceeds the 自己負担限度額, the insurer refunds the excess to you.
- 自己負担限度額 — the maximum you have to pay out of pocket that month, calculated in tiers by income category and age (under 70 / 70 and over).
- 限度額適用認定証 — a paper certificate you apply for from your insurer in advance; show it at the hospital and the counter bills you only up to the cap for that month.
- マイナ保険証 / オンライン資格確認 (onrain shikaku kakunin, online eligibility confirmation) — using the My Number card as your health insurance card; at hospitals that have introduced online eligibility confirmation, your cap information can be provided online, so you can pay only the cap at the counter even without a paper certificate.
- 支給申請書 / 高額療養費支給申請書 (shikyū shinseisho / kōgaku ryōyōhi shikyū shinseisho) — the application form you fill in to have the excess refunded afterward.
Common fields on the document
- 高額療養費 (kōgaku ryōyōhi) — High-Cost Medical Expense Benefit (the refund of the amount above the cap)
- 自己負担限度額 / 限度額 (jiko futan gendogaku / gendogaku) — self-pay cap
- 所得区分 / 標準報酬月額 / 課税所得 (shotoku kubun / hyōjun hōshū getsugaku / kazei shotoku) — the income classification (income category / standard monthly remuneration / taxable income) that determines which cap tier applies to you
- 限度額適用認定証 / 限度額適用・標準負担額減額認定証 (gendogaku tekiyō ninteishō / gendogaku tekiyō, hyōjun futangaku gengaku ninteishō) — certificate of application of the cap (low-income members have a separate "reduction certificate" that also reduces hospital meal charges)
- 多数該当 (tasū gaitō) — "multiple applicability"; if you have already hit the cap in 3 months within the past 12 months, the cap is lowered from the 4th month
- 保険者 (hokensha) — insurer (municipal National Health Insurance, Kyōkai Kenpo, health insurance societies, etc.)
- 支給申請 / 振込先口座 (shikyū shinsei / furikomisaki kōza) — refund application / bank account the refund is paid into
What you need to do
- If you expect high medical costs this month (e.g., surgery or hospitalization): arrange in advance for the counter to bill you only up to the cap that month, in either of these ways —
- use your マイナ保険証 at a hospital that has introduced online eligibility confirmation (in most cases no separate certificate is needed); or
- apply to your insurer in advance for a 限度額適用認定証 and show it when you receive care.
- If you already paid in full that month and only found out afterward: submit a 高額療養費支給申請書 to your insurer to claim a refund of the part above the cap (have your receipts, bank account details, and so on ready).
- Check your income category: the caps are tiered by income and age, so first check which tier you fall into (standard monthly remuneration / taxable income, etc.; the insurer's determination is what counts).
- Having someone act for you: the procedures do not necessarily have to be done by the insured person in person; a member of the same household or someone you authorize can usually act on your behalf (for National Health Insurance a 委任状, ininjō, letter of proxy, and identity documents are often required); follow your insurer's rules.
- If you cannot read a notice or application form you received: check with the insurer you are enrolled in or the Ministry of Health, Labour and Welfare — do not rely on guesswork.
Where the deadline / amount may appear
- "Same month" and monthly aggregation: the cap is basically calculated per calendar month (from the 1st to the end of the month), so pay attention to the dates of your visits and payments; within the monthly system there are also reductions such as 多数該当 (see below). There is a threshold for adding up multiple self-pay amounts within the same month: if you are under 70, only self-pay amounts of 21,000 yen or more each can be added up (counted per medical institution, with inpatient / outpatient / dental counted separately; co-pays at a dispensing pharmacy for out-of-hospital prescriptions are combined with the prescribing medical institution for this test); if you are 70 or over, everything can be added up.
- Do not look only at single months (annual aggregation / annual cap): under the current rules, outpatient care for those 70 and over already has annual aggregation — from August 1 to July 31 of the following year, if the annual total of outpatient self-pay in the general / low-income categories exceeds a set amount (144,000 yen for Kyōkai Kenpo and others; not applicable to the "income comparable to active workers" category, 現役並み所得者), it can be refunded. In addition, from August of Reiwa 8 (2026) a broader annual cap is planned to be introduced (see the revision reminder below). If you face long-term or repeated high medical costs, ask your insurer which aggregation mechanisms and amounts apply to you.
- Application time limit: applications for the after-the-fact refund generally have a limitation period (a set period counted from the month of treatment); if you miss it, you may no longer be able to claim. Check the exact deadline with your insurer.
- Cap amounts: written in the explanations about the cap, on the certificate, or in calculation tables, tiered by income category and age (under 70 / 70 and over); for the exact amount of each tier, rely on what the Ministry of Health, Labour and Welfare and your insurer publish — this article does not list specific figures.
- 多数該当 reduction point: if you have hit the cap in 3 months within the past 12 months, a lower cap applies from the 4th month.
Reminder: according to the Ministry of Health, Labour and Welfare, Japan plans staged revisions to the High-Cost Medical Expense Benefit from August of Reiwa 8 (2026), including adjustments to the caps and the introduction of a new "annual cap" (August through July of the following year: once your monthly self-pay amounts accumulate to the annual cap, the part beyond it can also be refunded by the insurer); from August of Reiwa 9 (2027), the income categories are to be subdivided further. For the exact effective dates and amounts, rely on the latest announcements from the Ministry of Health, Labour and Welfare; this article does not list figures that are not yet in effect.
Which official body to contact if you are unsure
For the general explanation of the system, rely on the Ministry of Health, Labour and Welfare website; for your specific cap, income category, application method, and time limits, rely on the explanations from the insurer you are enrolled in:
- National Health Insurance (Kokuho): the National Health Insurance counter of the municipality (市区町村, shikuchōson) where you live.
- Employee insurance: 協会けんぽ (Japan Health Insurance Association) or your company's 健保組合 (usually handled through your company).
Official explanations and your insurer's determination take precedence over any third-party interpretation.
Common Japanese terms
- 高額療養費 (kōgaku ryōyōhi) — High-Cost Medical Expense Benefit (refund of the amount above the cap)
- 自己負担限度額 (jiko futan gendogaku) — self-pay cap
- 限度額適用認定証 (gendogaku tekiyō ninteishō) — certificate of application of the cap
- オンライン資格確認 (onrain shikaku kakunin) — online eligibility confirmation
- マイナ保険証 (maina hokenshō) — My Number card used as a health insurance card
- 所得区分 / 標準報酬月額 (shotoku kubun / hyōjun hōshū getsugaku) — income category / standard monthly remuneration
- 多数該当 (tasū gaitō) — multiple applicability (a lower cap from the 4th month)
- 保険者 (hokensha) — insurer (municipal National Health Insurance, Kyōkai Kenpo, health insurance societies, etc.)
- 支給申請書 (shikyū shinseisho) — benefit application form (for the refund)