Do you assume the cap on your out-of-pocket medical costs is "around 80,000 yen a month under the High-Cost Medical Expense Benefit"? In fact, many health insurance societies (kenpo kumiai) at large companies offer an additional cap on top of that, called "fuka kyufu" (supplementary benefits) — a mechanism that keeps your actual out-of-pocket cost to roughly 20,000–25,000 yen per month. At most societies it requires no application and is paid automatically. It exists only for members of society-managed health insurance; Kyokai Kenpo and National Health Insurance have nothing like it. Now that the High-Cost Medical Expense Benefit caps were raised from August 2026, it is worth checking whether your own society offers supplementary benefits. We walk through everything, starting from how to check with nothing but your insurance card.
What supplementary benefits are: one more cap above the High-Cost Medical Expense Benefit
Supplementary benefits are extra payments that a health insurance society defines independently in its own bylaws. Separate from the High-Cost Medical Expense Benefit guaranteed to everyone by law (statutory benefits), the society sets its own threshold: "if your out-of-pocket cost in one month exceeds this amount, we refund the excess afterwards." The typical forms are the ichibu-futan kangen-kin (partial cost-sharing refund) for the insured person and the kazoku ryoyohi fuka-kin (family medical expense supplement) for dependents.
Thresholds vary by society, but many set them at 20,000–25,000 yen per month. Published rules of real societies look like this.
| Society (examples) | Name of benefit | Approx. effective out-of-pocket per month |
|---|---|---|
| Kanto IT Software Health Insurance Society | Partial cost-sharing refund | 20,000 yen (the excess is paid back) |
| Mitsui Health Insurance Society | Partial cost-sharing refund | 20,000 yen (pays your out-of-pocket cost minus 20,000 yen) |
| Fujitsu Health Insurance Society | Supplementary benefit | 25,000 yen (the excess is paid automatically) |
| Public School Mutual Aid Association (reference: public servants) | Partial cost-sharing reimbursement | 25,000 yen (50,000 yen if standard monthly remuneration is 530,000 yen or more) |
* From each society's published materials (as of August 2026). Each society has detailed rules on how costs are aggregated (per medical institution; inpatient and outpatient counted separately; etc.) and on rounding.
Worked example: an employee with 1,000,000 yen in medical bills and annual income of roughly 3.7–7.7 million yen (bracket U)
- 30% cost-sharing at the counter: 300,000 yen
- After the High-Cost Medical Expense Benefit (for treatment from August 2026): about 93,000 yen
- After supplementary benefits (society with a 20,000-yen threshold): final burden 20,000 yen — about 73,000 yen comes back later
Same medical bills, same income — yet depending on whether your insurer offers supplementary benefits, the final burden differs by more than four times.
The scale is not small either. According to the Ministry of Health, Labour and Welfare's health insurance annual report, in fiscal 2023 (Reiwa 5) society-managed insurers paid supplementary benefits of 1,752,000 claims / 69.8 billion yen for insured persons and 589,000 claims / 23.3 billion yen for family members. Combined, 2.34 million claims and 93.1 billion yen a year are actually being refunded. Around 80% of the claims are partial cost-sharing refunds and family medical expense supplements.
Only society-managed insurance has it — not Kyokai Kenpo or National Health Insurance
Supplementary benefits are independent payments a health insurance society funds out of its own finances, so whether you have them depends on which insurance you belong to.
| Your insurance | Supplementary benefits |
|---|---|
| Health insurance society (society-managed) — mainly employees of large companies and industry groups | Many societies have them (but not all, and the level varies by society) |
| Mutual aid associations — public servants, private-school staff | Have an equivalent "partial cost-sharing reimbursement" etc. (e.g., out-of-pocket above 25,000 yen) |
| Kyokai Kenpo — mainly employees of small and mid-sized companies | None (statutory benefits only) |
| National Health Insurance — self-employed, freelancers, etc. | None |
| Medical care system for the latter-stage elderly — age 75 and over | None |
It is also a "hidden gap in compensation"
Supplementary benefits almost never appear in job postings, yet they hugely affect your burden when serious illness strikes. Change jobs from a society-managed insurer to Kyokai Kenpo and the benefit disappears — and vice versa. When thinking about medical protection, treat "which health insurer you join" as an effective part of your compensation, alongside salary and bonuses, and you will judge more accurately.
Three steps to check whether your insurer offers supplementary benefits
- Look at the "insurer name" on your insurance card (eligibility certificate). If it says "XX Health Insurance Society" (kenko hoken kumiai), you are in society-managed insurance. "Japan Health Insurance Association" means Kyokai Kenpo, and "XX City" etc. means National Health Insurance — no supplementary benefits there. If you have switched fully to the Myna insurance card, you can also check the insurer name under "health insurance card information" on Myna Portal.
- Search your society's name and open the "insurance benefits" or "when medical costs are high" page on its official site. If you find the words "ichibu-futan kangen-kin," "fuka kyufu" or "fuka-kin," your society offers it. Note down the threshold (20,000 yen, 25,000 yen, etc.) and the unit of aggregation (per medical institution; inpatient and outpatient separate or not).
- Confirm "automatic or application-based" and the payment timing. Most societies compute it automatically from receipts (medical billing statements) and transfer it to your salary account or the like, but some require an application. If the site does not say, calling the society's office is the surest way.
If you suspect you missed past payments, look back through the society's "benefit payment decision notices" and the benefits column of your pay slips. The right to receive health insurance benefits expires in principle after two years, so if you forgot to apply at an application-based society, you may still be in time within two years.
How it relates to the High-Cost Medical Expense Benefit, the eligibility certificate and the August 2026 revision
Supplementary benefits are not a "replacement" for the High-Cost Medical Expense Benefit but an "add-on." The actual flow of money works like this.
- At the counter you pay up to the statutory cap. Using the Myna insurance card (or a certificate of eligibility for the cap), your counter payment stops at the High-Cost Medical Expense Benefit ceiling. The supplementary benefit does not lower the counter payment itself (though some societies do reduce it on their own).
- A few months later the supplementary benefit is paid in. The society determines your out-of-pocket amount from receipts and later refunds the portion above its threshold (20,000 yen etc.). Payment about three months after the month of treatment is typical.
And from August 2026, the High-Cost Medical Expense Benefit caps were raised (for bracket U, from 80,100 yen to 85,800 yen per month plus a 1% add-on, a new annual ceiling, and more). This is where supplementary benefits gain real significance.
If you have supplementary benefits, the increase barely touches you
Because the benefit "refunds whatever exceeds the threshold," even if the statutory cap rises, your final out-of-pocket stays around 20,000 yen a month as long as the society keeps its threshold unchanged (the society's benefit spending absorbs the increase). On the other hand, the higher statutory caps increase the burden on health insurance societies, so some societies may consider raising or scaling back their thresholds going forward. Keep an eye on notices from your own society (its magazine or website news).
Points to watch: excluded costs, payment timing and the medical expense deduction
- Some costs are excluded. Hospital meal charges, extra charges for private rooms, technology fees for advanced medical treatment, non-covered (free) care and other costs outside the High-Cost Medical Expense Benefit are not refunded by supplementary benefits either. When planning medical protection, the fact that "this is where costs can become unlimited" does not change even with supplementary benefits.
- You front the money for a while. Payment comes about three months after the month of treatment. You must first pay up to the statutory cap (around 90,000 yen a month) at the counter, so cash on hand is still needed.
- Detailed conditions differ by society. Fine rules vary: "calculated per medical institution, inpatient and outpatient separately," "no payment if the computed amount is under 1,000 yen," "amounts under 100 yen rounded down," and so on. Also, portions covered by municipal medical subsidies (such as children's medical subsidies) are generally excluded.
- Deduct it from the medical expense deduction. Like the High-Cost Medical Expense Benefit, supplementary benefits count as "amounts compensated by insurance or the like," so when claiming the medical expense deduction you subtract the supplementary benefits received (or expected) from those medical costs. If the amount is not fixed at filing time, use an estimate, and if it turns out different, adjust with an amended return or a request for correction.
- The level is not guaranteed forever. Supplementary benefits can be scaled back or abolished depending on the society's finances. Rather than concluding "I have supplementary benefits, so private medical insurance is entirely unnecessary," weigh excluded costs and the risk of income loss, and judge your need for coverage comprehensively.
What to do today
What to do today
- Check the insurer name on your insurance card (eligibility certificate or Myna Portal) — if it is "XX Health Insurance Society," supplementary benefits may exist
- Find the "partial cost-sharing refund" or "supplementary benefits" page on your society's official site and note the threshold, whether it is automatic or application-based, and the unit of aggregation
- If in the past two years you had a month with more than 20,000 yen in medical costs, review your benefit payment notices, and if nothing was paid, ask your society (the limitation period is in principle two years)
FAQ
Q. Do I have to apply to receive supplementary benefits?
A. Most health insurance societies calculate them automatically from the receipts sent by medical institutions and transfer the money to your salary account, so no application is needed. However, some societies are application-based, and cases such as reimbursement claims or treatment abroad may not be automatic. Check your society's method on its official site or by phoning its office.
Q. When is it paid?
A. About three months after the month of treatment is typical (the society waits for receipts to be finalized). While employed, many societies pay via your employer together with salary; during voluntary continued coverage it is transferred to a registered account. Until then you must front the money up to the statutory cap.
Q. Do Kyokai Kenpo or National Health Insurance have supplementary benefits too?
A. No. Supplementary benefits are add-ons that health insurance societies provide independently under their bylaws; Kyokai Kenpo, National Health Insurance and the latter-stage elderly system provide only statutory benefits such as the High-Cost Medical Expense Benefit. Mutual aid associations for public servants and private-school staff do have an equivalent "partial cost-sharing reimbursement" (e.g., out-of-pocket above 25,000 yen).
Q. Will the August 2026 increase in the High-Cost Medical Expense Benefit caps raise the burden for people with supplementary benefits?
A. As long as the society keeps its threshold unchanged, your final out-of-pocket stays at the threshold (around 20,000 yen a month) and in principle does not increase; the society's benefit spending covers the difference. However, given the impact on society finances, thresholds may be reviewed in the future, so check notices from your society.
References (sources)
* Figures and rules are based on materials published as of August 2026. The existence, thresholds and payment methods of supplementary benefits differ by health insurance society, so always check your own society's bylaws and official site. This article is general information; for individual decisions, consult your health insurance society, a tax office or a professional.