Japan's Medical Expense Deduction Explained: How to Calculate It and What Qualifies
If you've had a year with high medical bills in Japan, there's a good chance you're entitled to a tax refund — and many people miss it simply because they don't know it exists. The system is called the medical expense deduction (医療費控除, iryo-hi koujo), and it can meaningfully reduce your income tax and residence tax burden.
This guide walks you through how it works, what qualifies, and the practical steps to claim it — including a lesser-known alternative for years when your medical costs stay under the threshold.
How the Medical Expense Deduction Works
The deduction applies to medical costs paid between January 1 and December 31 of a given year. If your qualifying expenses exceed a threshold, the excess amount is deducted from your taxable income, reducing what you owe.
The formula is straightforward:
Deductible amount = Total qualifying medical expenses paid
− Insurance reimbursements received
− ¥100,000 (or 5% of total income, whichever is lower)
A concrete example: Say your medical expenses for the year totaled ¥180,000, and your health insurance reimbursed ¥20,000 of that.
¥180,000 − ¥20,000 − ¥100,000 = ¥60,000 deductible
If your income tax rate is 20%, that ¥60,000 deduction translates to roughly ¥12,000 refunded.
One important exception: If your total annual income is under ¥2,000,000, the threshold is not ¥100,000 but rather 5% of your total income. For example, at ¥1,800,000 income, the threshold drops to ¥90,000 — meaning you reach the deduction earlier.
What Qualifies — and What Doesn't
The core principle is whether the expense was medically necessary for diagnosis, treatment, or care. Cosmetic or purely preventive costs generally don't qualify.
Expenses that qualify
- Hospital and clinic fees, including transportation costs to get there (public transit counts; personal car fuel does not)
- Prescription medications purchased at a pharmacy with a valid prescription
- Hospitalization costs, including the standard meal allowance (note: optional private room upgrades may not qualify)
- Dental treatment: fillings, extractions, and medically necessary implants qualify; teeth whitening does not
- Fertility treatments, including artificial insemination
- Out-of-pocket costs for nursing care insurance services (partial)
Expenses that don't qualify
- Routine health checkups and cancer screenings — with one exception: if a checkup finds something that leads directly to treatment, the checkup fee may then qualify
- Over-the-counter supplements and preventive medications: these are not considered treatment
- Cosmetic surgery unless there is a clear medical necessity
- Prescription eyeglasses and contact lenses for standard vision correction (glasses for conditions like strabismus may qualify)
- Prenatal checkup fees (though costs directly related to childbirth do qualify)
A gray area worth noting — dental braces: Orthodontic treatment for children to correct developmental issues is generally accepted as medically necessary and qualifies. Braces for adults seeking cosmetic alignment typically don't. If you're unsure, ask your dentist to document the medical necessity in writing — it can make a real difference at filing time.
Can You Claim Expenses for Your Family?
Yes — and this is one of the most valuable aspects of the deduction. You can combine the medical expenses of all family members who share a household budget (生計を一にする, seikei wo ichi ni suru) and file them together under a single return.
For dual-income couples, it generally makes more sense for the higher earner to file the claim, since the tax savings scale with your marginal rate.
The "shared household budget" standard doesn't require living together. If you financially support a parent or child living separately — through regular remittances, for example — their expenses can still be included. However, a family member who is fully financially independent does not qualify.
On receipts: Since 2017, you no longer need to attach receipts to your tax return. That said, you are required to keep them for five years in case of an audit. Organizing them by family member and provider as you go makes filing much easier.
What If You Don't Reach ¥100,000? The Self-Medication Tax System
If your medical expenses fall short of the ¥100,000 threshold, don't assume you have no options. Japan has a parallel system called the Self-Medication Tax System (セルフメディケーション税制, self-medication zeisei) — a deduction designed for people who rely more on over-the-counter medicines than on hospital visits.
To be eligible, you must have undergone at least one qualifying health checkup or vaccination during the year. If you meet that condition and your spending on qualifying switch OTC drugs (pharmaceuticals that were previously prescription-only and are now available over the counter) exceeds ¥12,000 in a year, you can deduct the excess.
| Medical Expense Deduction | Self-Medication Tax System | |
|---|---|---|
| Eligible expenses | Medical care broadly | Specific OTC switch drugs only |
| Threshold | ¥100,000 (or 5% of income) | ¥12,000 |
| Maximum deduction | ¥2,000,000 | ¥88,000 |
| Prerequisite | None | Must have a qualifying checkup or vaccination |
You can choose whichever system benefits you more each year, but you cannot use both at the same time. In a year with heavy hospital costs, the standard deduction usually wins. In a year where you're mostly buying cold medicine and allergy drugs, the Self-Medication system may be the better fit.
How to File and Where to Start
Unlike year-end tax adjustments handled by your employer (nenmatsu chosei), the medical expense deduction must be filed by you directly as part of a kakutei shinkoku (確定申告, annual tax return). This applies even if you're a full-time employee.
The standard filing window is February 16 to March 15 of the following year. However, if you're filing purely to claim a refund — which is the case for most people claiming the medical expense deduction — you can file any time from January 1, and you have up to five years to go back and claim previous years you may have missed.
To estimate how much you might get back before you start gathering documents, the Zeicalc calculator is a useful starting point. It covers the medical expense deduction alongside other common deductions for Japan-based filers, including the furusato nozei hometown tax donation system and side income thresholds.
Before sorting through every receipt, a quick calculation can tell you whether it's worth filing at all. If your annual medical spending looks like it will clear ¥100,000, the habit worth building is simple: keep every receipt from hospitals, clinics, and pharmacies in one place throughout the year.
A Note from the Author
Honestly, I didn't know for a long time that you could combine medical expenses across your whole family, or that you could file retroactively for up to five years. I kept no receipts, no records — nothing. When I finally learned what I'd missed, I wished someone had told me sooner. That's a big part of why I wrote this.