This is a translation of the Japanese original. The Japanese version is authoritative; figures follow Japanese tax law.
A part-timer covered as a dependent on a spouse's health insurance keeps working without noticing that annual income has passed 1.3 million yen, and the autumn "dependent status recheck" brings it to light. At that point the dependent status is deleted not from the day you are told, but retroactively from the day your income stopped meeting the standard, and you are asked to repay the 70 percent of the medical costs the health insurance provider paid for the treatment you received in the meantime. Most of that 70 percent comes back if you enrol retroactively in National Health Insurance (NHI) and file a claim for medical expense reimbursement, but the backdated NHI premiums and National Pension contributions leave your pocket for good. Another trap is the asymmetry of the time limits: the repayment demand has a long one, while your claim against NHI expires in two years. This article sets out what to do and in what order, using materials from the Japan Health Insurance Association, health insurance societies and municipalities.
The short answer: three things to do, and the wrong order costs you the money
- Repay 70 percent to the health insurance provider. For treatment received on or after the removal date, a demand arrives for what the provider paid the medical institution (as a rule 70 percent of the total medical costs). Once you have paid, always obtain the receipt proving the repayment.
- Enrol in NHI and the National Pension retroactively to the "removal date". Go to your municipal office with the certificate of loss of health insurance coverage. The enrolment date is not the day you file but the day you came off the dependent status, and premiums run from that month.
- File a medical expense reimbursement claim with NHI. Claim the 70 percent you repaid from the NHI you have just joined retroactively, as a "medical expense reimbursement". It expires two years from the first day of the month after the month of treatment, so run it in parallel with the repayment.
Sources: health insurance society guidance, "A demand to repay my wife's medical costs arrived from the health insurance society - what is this?" [Nagase & Co. Health Insurance Society], Gifu City, "Enrolling in National Health Insurance after coming off dependent status" [Gifu City], Sapporo City, "National Health Insurance (FAQ)" [Sapporo City]
The health insurance society's own guidance says to "contact the society that issued the repayment demand, obtain the receipt for the repayment, and tell your newly joined insurer that a repayment demand was made". NHI pays a reimbursement on the premise that the treatment falls in a period when you should properly have been an NHI member, so the basic flow is to complete the retroactive NHI enrolment first and then file with the proof of repayment attached.
Why it is "retroactive": the removal date is the day your income went over
A health insurance dependent must have an annual income of under 1.3 million yen (under 1.8 million yen if aged 60 or over or disabled), and this 1.3 million yen is judged not on past results but on the "outlook for the coming year". From the moment income of 108,334 yen a month or more is expected to continue, you stop meeting the requirement from that day, and the rule is that the removal should be filed there and then (within five days)[Japan Health Insurance Association].
If no filing is made and the autumn recheck uncovers it (the Japan Health Insurance Association sends employers a "dependent status list" from late October every year; for fiscal 2025 the deadline for returning it is December 12), the removal date goes back to the day you stopped meeting the requirement - the day your hourly rate rose, the first day of the month your hours increased, and so on. Going back six months is not unusual.
What it actually costs: the money that comes back and the money that does not
Take the case where the removal goes back to April and, in the meantime, you received outpatient care and a short hospital stay totalling 300,000 yen in medical costs (90,000 yen of that paid at the counter as the 30 percent share).
| Item | Amount (example) | Does it come back? |
|---|---|---|
| Repayment to the health insurance provider (70% of 300,000 yen) | 210,000 yen | As a rule yes, via the NHI reimbursement (subject to review; claim within two years) |
| Backdated NHI premiums (April to December, nine months) | About 80,000 to 100,000 yen | No (premiums you should properly have paid) |
| Backdated National Pension contributions (Category 3 to Category 1; 17,920 yen a month x 9 months) | About 160,000 yen | No, but it counts towards your future pension |
| A different bracket for the high-cost medical expense benefit | - | Recalculated under NHI. If the household income bracket changes, so does your out-of-pocket ceiling |
Even assuming the 70 percent you repaid comes back, the backdated NHI premiums and National Pension contributions take 200,000 to 350,000 yen a year out of your pocket. That is simply what "going over 1.3 million yen means coming off dependent status" amounts to, but in a retroactive case you pay several months at once, and you were working "on the assumption you were a dependent" the whole time, so the plan for your take-home pay falls apart. If you went over 1.3 million yen by only a little, the excess is wiped out entirely. You can check a rough figure for NHI premiums in calculating National Health Insurance premiums.
For the National Pension, while you are a dependent on your spouse you are a Category 3 insured person, and the months count towards your record without any contribution. Come off the dependent status retroactively and you lose the Category 3 status from the same day, so you must pay 17,920 yen a month as a Category 1 insured person (fiscal 2026). Paying it does increase your future pension, but the payment slips arrive all at once and the hit to the household budget is heavy. If you cannot pay, ask a pension office whether you can apply retroactively for an exemption or deferral (as a rule as far back as two years and one month).
The asymmetry of the time limits: long for the side demanding, two years for the side recovering
This is the least known point of all.
- The repayment demand from the health insurance provider is a claim under the Civil Code for the return of unjust enrichment, because benefits were paid to someone who was not covered. The limitation period is the same as for ordinary civil claims - five years from when the insurer became aware of it (ten years from when the right could be exercised) - so treatment from several years back can be demanded.
- A medical expense reimbursement claim against NHI expires under the National Health Insurance Act two years from the first day of the month after the month of treatment.
- Backdated assessment of NHI premiums also runs up to two years (Sapporo City states "up to 26 months")[Sapporo City].
In other words, if the removal date goes back more than two years, there is a period you must repay to the health insurance provider but cannot recover from NHI. Cases uncovered by the recheck are usually within a year, so most people are covered, but if the requirement went unmet for several years the damage is of a different order. When a repayment demand arrives, first check the removal date and the months of treatment, and file with NHI starting with the months whose two-year deadline is closest.
When NHI allows the reimbursement, and the cases most likely to be refused
NHI guidance says that "if the filing is late, medical costs up to the day before the filing are in principle entirely at your own expense"[Sapporo City]. That said, many municipalities anticipate retroactive removal and invite you to discuss a reimbursement, as Gifu City does: "if you could not complete the procedure within 14 days because, for example, you came off dependent status retroactively, and you have seen a doctor, please consult us"[Gifu City].
Likely to be allowed
- The removal was made retroactively by the recheck or an insurer's investigation, and you had no opportunity to file
- You have completed the repayment to the health insurance provider and attach the receipt and a copy of the medical fee statement (the receipt of treatment details)
- You filed with NHI within 14 days of the removal date (you acted as soon as the removal notice arrived)
May be refused
- You knew yourself that your income had gone over, did not file, and went on using the health insurance coverage
- You left the NHI procedure for a long time after receiving the removal notice
- More than two years have passed since the month after the month of treatment
The claim needs the "receipt for the repaid amount" issued by the health insurance provider and the treatment details attached to the repayment demand (name of the medical institution, month of treatment, insurance points). Telling the provider, when you repay, that you "will be claiming a medical expense reimbursement from NHI, so please leave me the details" saves you having to go back later.
Better still, never let it go retroactive: act when you are about to go over
- Know that it is judged on the outlook. It is not "if you go over 1.3 million yen by the end of the year"; you fall outside the requirement from the moment 108,334 yen a month or more is expected to continue. The right move is to raise it with your spouse's employer in the month your shifts increase. The requirements are set out in detail in health insurance dependent status.
- If the rise is temporary, an "employer's certification" lets you stay. Where you go over 1.3 million yen for a temporary reason such as busy-season overtime, there is a mechanism to keep your dependent status through your workplace's certification (as a rule up to two consecutive times). See how to obtain the employer's certification.
- From October 2026 more people join at their own workplace first. If you work 20 hours a week or more for an employer with more than 50 employees, you join your workplace's social insurance whatever your wage. In that case coming off the dependent status leads not to NHI and the National Pension but to your workplace's health insurance and employees' pension, so the cost of a retroactive case is replaced by your workplace's premiums. For the wider picture, see the 1.06 million yen and 1.3 million yen walls.
- When the removal notice arrives, go to NHI that week. Filing within 14 days works in your favour when the reimbursement is reviewed.
Frequently asked questions
I cannot afford to pay the repayment first. Can I receive the NHI reimbursement before that?
As a rule NHI will not pay a reimbursement without proof that you have repaid the health insurance provider. Some insurers settle directly between the health insurance provider and NHI, so tell both the contact on the repayment demand and your NHI counter that paying is difficult. Some providers will accept instalments.
How long can I pay the contributions for the period in which I became a Category 1 National Pension insured person retroactively?
You can pay within two years of the due date. If paying it all at once is difficult, you can apply retroactively for an exemption or deferral (back to the month two years and one month before the date of application). Leave it unpaid beyond two years and that month does not count towards your record, reducing your future pension.
Summary
- Dependent status is removed retroactively to the date income exceeded the threshold, and you are required to repay the 70% that health insurance covered during that period.
- You are enrolled retroactively in National Health Insurance and National Pension back to the removal date, and the 70% you repaid can be claimed from National Health Insurance as a medical expense reimbursement.
- Retroactive National Health Insurance and National Pension premiums are not refunded. The National Pension premium is 17,920 yen a month (FY Reiwa 8 / 2026).
- Claims to National Health Insurance for medical expense reimbursement expire two years from the first day of the month after treatment. File first for the treatment months closest to their deadline.
- The 1.3 million yen threshold is judged on projected income. Consult your spouse's company as soon as monthly income is projected to continue at 108,334 yen or more.
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Reference links (sources)
This article is based on the materials below. Because how the removal date is set and how a reimbursement is reviewed differ between insurers and municipalities, please check at the counter before you start.
Note: this article is general information. The example amounts are estimates and vary with the medical costs and the municipality. For an individual decision, check with your health insurance provider or your municipality.