Medical Expense Deduction Calculator (Japan Iryohi Kojo)

Enter your annual medical expenses, insurance reimbursements, and total income to estimate the medical expense deduction and the resulting income and resident tax refund under Japan's official tax formula (Income Tax Act Article 73).

Last updated: 2026-09-19

What Japan's medical expense deduction (Iryohi Kojo) is

The medical expense deduction is an income deduction available when the medical costs you paid during a calendar year (January 1 to December 31) — for yourself or family members who share your livelihood — exceed a certain threshold. It is set out in Article 73 of the Income Tax Act, and unlike most deductions for salaried employees, it is never applied automatically through year-end tax adjustment (nenmatsu chosei); you must file your own final tax return (kakutei shinkoku) to claim it, even if your employer otherwise withholds and settles your tax in full. The deductible amount is worked out by taking the total medical expenses you paid, subtracting any amounts reimbursed by insurance (such as payouts or the high-cost medical expense benefit), and then subtracting a threshold — 5% of your total income if that income is under 2 million yen, or a flat 100,000 yen otherwise.

This calculator turns those inputs — your annual medical expenses, any reimbursements, your total income, and your income tax bracket — into an estimate of the deduction amount, the income tax refund you could expect from filing, and the reduction to next year's resident tax. It's designed to give you a quick sense, before you start gathering receipts or filling in the paperwork, of whether a year with heavy medical spending (a hospitalization or surgery, for example) is worth the effort of filing a return.

Sources used in this calculation

Statutory figures such as tax and insurance rates come from the public bodies listed below. They change when the law is revised, so please also check the primary source before relying on the result for an important decision.

Japan medical expense deduction amount & threshold — National Tax Agency (国税庁) Effective from 2017-01 ／ Last checked 2026-09-09

How we source and maintain these figures

How to use the medical expense deduction calculator

Enter your total medical expenses for the year Add up everything paid between January 1 and December 31 for yourself and family members who share your livelihood, including public transport fares for hospital visits.
Enter any amount reimbursed by insurance Include hospitalization benefits from life insurance, the high-cost medical expense benefit, the childbirth lump-sum allowance, and similar payouts. Leave it at zero if you received none.
Enter your total income Use the figure before deductions, such as the "amount after employment income deduction" on your withholding statement. This determines whether your threshold is 100,000 yen or 5% of income.
Select your income tax bracket Choose the rate that matches your taxable income. It's used to estimate the income tax refund.
Review the deduction and refund estimate The tool displays the deduction amount, the estimated income tax refund, and the estimated reduction to next year's resident tax together.

Tips for getting more out of it

Transportation costs for hospital visits (actual public transit fares) also qualify for the deduction. Taxi fares only qualify when public transit genuinely wasn't an option, such as an emergency.
You can combine medical expenses paid for family members who share your livelihood (a spouse or dependents you support), so gathering receipts for the whole household can help maximize the deduction.
Filing through e-Tax lets you skip attaching receipts, and you can use the data from the "medical expense notification" sent by your health insurer to reduce the work of preparing the statement.
Cosmetic procedures, supplements for general health promotion, and routine health checkups (when no abnormality is found) are generally excluded — whether the expense was for treatment is the deciding factor.

When this calculator is useful

Deciding whether to file after a hospitalization or surgery

In a year when medical costs jumped because of a hospital stay or an operation, check the likely refund before committing time to preparing a return.

Adding up medical bills across the whole household

Enter the combined receipts for a spouse, parents, or children who share your livelihood to see how much deduction the household could claim in total.

Getting figures ready before filing through e-Tax

Knowing the rough deduction and refund amount in advance makes it easier to fill in the statement of medical expense deductions when you sit down to e-file.

Weighing the paperwork against a marginal benefit

If your expenses barely clear the threshold, checking the estimated refund helps you judge whether preparing the statement is worth the time.

Comparing against the self-medication tax system

If you bought a lot of over-the-counter medicine during the year, compare this result with the self-medication tax system calculator to see which deduction is larger. Checking the high-cost medical expense benefit calculator first also helps you estimate your net medical cost more accurately.

Medical expense deduction glossary

Medical expense deduction (Iryohi Kojo): An income deduction under Article 73 of the Income Tax Act, available when your annual medical expenses exceed a threshold. It is never applied through year-end adjustment, so anyone eligible must file their own return to claim it.
Final tax return (Kakutei Shinkoku): The annual filing in which you calculate your income and tax for the year and report it to the tax office. Since the medical expense deduction falls outside year-end adjustment, even salaried employees need to file one to claim it.
Total income: The sum of all income types — employment income, business income, miscellaneous income, and so on — before any of the various income deductions are applied. It decides whether your threshold is a flat 100,000 yen or 5% of income.
Marginal (income) tax rate: The tax rate bracket that applies to your taxable income, which rises in steps. The estimated income tax refund is calculated by multiplying the deduction amount by this rate.
Self-medication tax system: A separate income deduction based on purchases of certain over-the-counter drugs (switch OTC medicines). It is mutually exclusive with the medical expense deduction — you must choose one or the other for the same year.
Refund: Income tax that was over-withheld or over-paid during the year and gets settled back to you once you file your return. For the medical expense deduction, the deduction amount multiplied by your tax rate gives a rough estimate of the refund.
Threshold amount: The baseline subtracted from your medical expenses to work out the deductible amount. It is 5% of total income if that income is under 2 million yen, or a flat 100,000 yen otherwise.

FAQ

The high-cost medical expense benefit is an insurance payout refunded by your health insurer, while the medical expense deduction is a tax deduction claimed on your return. Since the deduction is based on your net cost after subtracting any high-cost medical benefit refund, finalize that refund amount first before filing the medical expense deduction.

If your total income is 2M yen or more, expenses (net of reimbursements) exceeding 100,000 yen qualify. If your total income is under 2M yen, the threshold is 5% of your total income instead of 100,000 yen, so you can qualify with lower medical expenses.

Medicines recognized as necessary for treatment or recuperation qualify. Vitamins and supplements intended for general health promotion or prevention rather than treatment do not. Check with your local tax office or the National Tax Agency's Tax Answer site if you're unsure.

You need a "statement of medical expense deductions" (simplified if you have a medical expense notification) and your tax return. Receipts no longer need to be submitted, but you must keep them for 5 years in case the tax office requests them.

Side Note — Why the medical expense deduction has two different thresholds

The reason the deduction threshold switches from a flat 100,000 yen to "5% of income" for those with total income under 2M yen is a fairness design that accounts for differing ability to pay across income levels. If the threshold were a flat 100,000 yen for everyone, that amount would weigh relatively more heavily on lower-income households, making it harder for them to benefit from the deduction. Setting the bar at 5% of income lets lower-income households qualify from a smaller medical expense burden, bringing the relief closer to parity across income levels.

The deduction draws its line at whether an expense was for "treatment," because the underlying rationale for the tax deduction is relief for a reduced ability to pay taxes caused by unavoidable spending due to illness or injury. Cosmetic surgery or supplements for general health promotion are discretionary expenses that don't represent a reduced ability to pay, so they fall outside the deduction even though they're still spending related to one's body. This line is one of the most frequently asked-about points at tax offices every year.

Starting with the 2017 tax year filing, attaching or presenting receipts was no longer required by default — instead, submitting a "statement of medical expense deductions" became mandatory. This change was driven by the spread of electronic tax filing (e-Tax) and the introduction of the My Number system, aiming to simplify the filing process by using the "medical expense notification" data issued by health insurance associations. However, the obligation to retain the receipts themselves for 5 years remains, since a tax audit could still require you to present them even after preparing the statement.

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