Which Spouse Should Claim Japan's Medical Expense Deduction? Conditions for Combining Family Costs
Under Japan's medical expense deduction, one person can claim the combined costs of family members who share living expenses. In a dual-income couple, either can generally file, and who gets more back depends on both income tax rate and threshold. This article covers which family members can be combined, compares who should file using real amounts, and explains what to watch for if you file separately.
One person can claim the whole family's medical costs
The deduction covers your own medical costs plus those you paid for "a spouse or other relatives who share living expenses with you". You total the whole family's costs, and one person files.
- Dependent status doesn't matter: even if your spouse has their own income in a dual-income household, costs can be combined as long as you share living expenses
- You don't have to live together: a spouse posted away for work, a child living alone for school or a parent you support with remittances counts as sharing living expenses if you regularly send living costs
- The person who paid files: the deduction belongs to whoever actually bore the cost. Couples with one household budget usually have one of them file for the family
- The same medical costs can't be claimed by two people
Whether you "share living expenses" is judged by whether you live from the same purse. A relative in the same house who manages living costs entirely separately isn't included.
Who gets more back?
The amount returned is income tax (deduction × income tax rate) plus resident tax (deduction × 10%). Resident tax's 10% is the same for everyone, so the person with the higher income tax rate (the higher salary) is usually the better filer. There are 2 exceptions.
- A family member with income under 2 million yen has a threshold below 100,000 yen, so when costs are small, the larger deduction can reverse the result
- A family member who pays no income tax or resident tax gets nothing back by filing
Comparison by salary combination
These are the amounts returned (income tax refund + resident tax reduction) when either the husband or the wife files for the family's total medical costs, for an employee couple under 40.
| Husband / wife salary | Total medical costs | Husband files | Wife files |
|---|---|---|---|
| 6 million / 1.5 million yen | 80,000 yen | 0 yen | 3,800 yen |
| 6 million / 1.5 million yen | 150,000 yen | 10,105 yen | 10,800 yen |
| 6 million / 1.5 million yen | 300,000 yen | 40,420 yen | 19,800 yen |
| 5 million / 1 million yen | 300,000 yen | 40,420 yen | 0 yen |
| 8 million / 4 million yen | 300,000 yen | 60,840 yen | 30,210 yen |
| 4 million / 4 million yen | 300,000 yen | 30,210 yen | 30,210 yen |
For a couple earning 6 million and 1.5 million yen, the wife gets more back with costs up to 150,000 yen. Her threshold is 42,500 yen, which makes her deduction 107,500 yen, larger than her husband's 50,000 yen. At 300,000 yen in costs, she pays no income tax and her resident tax reduction tops out at 19,800 yen, so her husband, at a 10% tax rate, gets more than twice as much by filing.
A wife earning 1 million yen pays neither income tax nor resident tax, so she gets 0 yen back however large the deduction. For a couple with equal salaries, the amount is the same whichever files.
Filing separately tends to cost you
Each spouse can also file their own share: the husband for costs he paid, the wife for costs she paid. But the 100,000-yen threshold then applies to each, so combining is better in almost every case.
Also watch the combination with other deductions. If your income tax is already zero thanks to the housing loan deduction, the medical expense deduction may not add to your income tax refund. If you use furusato nozei, the lower income from the medical expense deduction also lowers your limit slightly (furusato nozei with iDeCo and the medical expense deduction).
Family cases that are easy to get wrong
| Case | Can costs be combined? |
|---|---|
| Dual-income spouse who isn't a dependent | Yes (if you share living expenses) |
| University student child living alone whom you send money to | Yes |
| Parent living apart whom you send money to every month | Yes (if you regularly send living costs) |
| Parent living with you whose living costs are completely separate | No |
| Medical costs your spouse paid before marriage | No (living expenses were separate at the time) |
| Deceased family member's medical costs paid after death | If paid by someone who shared living expenses, they count toward that person's deduction |
The deduction is judged by whether you shared living expenses when the costs were paid, not as of December 31 of that year. In the year you marry, you can combine your spouse's costs paid after the marriage.
Compare filers with the tool
In the Who should file? tab of the Medical Expense Deduction Refund Calculator, enter the salaries and ages of up to 4 family members and the family's total medical costs. It lists the deduction and amount returned for each filer, highest first. You can see directly that a family member who pays no tax gets nothing back, and how different thresholds reverse the result.
The conditions that lower the threshold are covered in whether you can claim under 100,000 yen, and how to calculate the tax returned from the deduction in how much the medical expense deduction returns.
FAQ
- In a dual-income couple, who should claim the deduction?
- As a rule, the spouse with the higher income tax rate (the higher salary) gets more back. But if one spouse's income is under 2 million yen and costs are small, the lower earner with the smaller threshold may do better. Someone who pays no income tax or resident tax gets nothing back.
- Can my non-dependent wife's medical costs go on my deduction?
- Yes. Whether costs can be combined depends on whether you share living expenses, not on dependent status. Even in a dual-income household, they can be combined if the household budget is shared.
- Can I include medical costs for a parent living apart?
- Yes, if you share living expenses, such as by regularly sending money, and you paid the costs yourself. Costs your parent paid from their own pension count toward their own deduction.
- Can spouses file medical costs separately?
- Each can file what they actually paid, but the 100,000-yen threshold applies to each, so the amount returned is almost always less than when one person files for both.
Tools in this article
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