High-Cost Medical Expense Benefit (Kōgaku Ryōyōhi)

What the benefit does

Japan’s health insurance system caps a household’s monthly out-of-pocket medical costs through the high-cost medical expense benefit (高額療養費, kōgaku ryōyōhi). If your medical bills in a single month exceed your income-bracket threshold, the insurance fund reimburses the excess. The ceiling applies per calendar month, across all medical institutions and pharmacies billing under the same insurance scheme.

This prevents catastrophic out-of-pocket spending during serious illness, hospitalization, or surgery. The benefit exists in both NHI and shakai hoken, with nearly identical structure.

Income brackets and the ceiling calculation

The monthly ceiling is not a fixed number. It is calculated using a formula that depends on which of five income brackets you belong to. Brackets are determined by annual taxable income and are updated periodically by MHLW. As a general orientation for 2024–2025:

• Bracket A (Annual income over ¥9 million): approximately ¥252,600 + 1% of costs above ¥842,000
• Bracket B (¥6–9 million): approximately ¥167,400 + 1% of costs above ¥558,000
• Bracket C (Standard, ¥3.7–7.7 million): approximately ¥80,100 + 1% of costs above ¥267,000
• Bracket D (Low income, ¥2.1–3.7 million): approximately ¥57,600
• Bracket E (Residents exempt from municipal tax): approximately ¥35,400

The insurance fund compares your total monthly copayments across all providers to the threshold, and reimburses the amount above it. Note that meal fees during hospitalization, room amenity charges, and non-covered services are excluded from the calculation.

The eligible limit certificate — avoiding the upfront payment

The standard process for the benefit is retroactive: you pay the full 30% at the time of service, then apply for reimbursement after the month ends. This creates a short-term cash flow burden during expensive hospitalizations.

The eligible limit certificate (限度額適用認定証, gendogaku tekiyō ninteishō) solves this. With the certificate, you present it to the hospital at admission alongside your insurance card. The hospital adjusts the checkout amount to the ceiling for your bracket; you do not need to pay more than the ceiling upfront and then wait for reimbursement.

For NHI, apply at your municipal office’s health insurance counter, typically a week or more before a planned hospitalization. For shakai hoken through Kyōkai Kenpo, applications can be made online through the insurer’s portal. Company-specific health insurance society procedures vary — check with your HR department.

Multiple-month and household provisions

If your monthly costs exceed the ceiling for three separate months within a twelve-month period, the ceiling decreases from the fourth month onward under the multiple-month special rule (多数回該当, tasū-kai gaitō). This recognizes that prolonged expensive treatment is more burdensome than a single month of high costs.

Household combining (世帯合算, setai gassan) allows all household members enrolled in the same insurance scheme to pool their copayments for the monthly calculation. If one member’s costs alone do not reach the threshold but the household’s combined costs do, the household can still claim the benefit. Bring itemized receipts and identification for all household members when applying.

How to apply for reimbursement

For NHI, apply at your municipal office approximately three to four months after the billing month ends (the exact processing window varies by municipality). Bring itemized receipts (明細書, meisaisho), your insurance card, your bankbook or bank account details for reimbursement, and any certificate of benefit you have been issued. Most shakai hoken insurers notify eligible recipients automatically, but you may still need to submit a reimbursement claim form.

Last reviewed: September 2026