Pay a Child's National Pension, Deduct the Full Amount

Bottom line: the deduction goes to whoever paid, so the person with the higher tax rate should pay

The National Tax Agency states that, for the social insurance premium deduction, "where a taxpayer pays social insurance premiums that are payable by the taxpayer or by a spouse or other relative sharing living expenses (seikei o itsu ni suru) with the taxpayer, the amount paid may be claimed as an income deduction," and that the deductible amount is the full amount actually paid during the year [NTA No.1130].

There are two key points. The first is "sharing living expenses". Living together normally satisfies this, and living apart also satisfies it if you send money that supports the other person's living costs. The second is that you actually paid. Premiums withheld from a pension, or debited from the family member's own account, are that family member's deduction.

How much you save: who pays can make a difference of more than 60,000 yen

The social insurance premium deduction is an income deduction, so the saving equals "the deduction amount multiplied by that person's tax rate." A student with no income owes no tax, so the deduction is worthless in their hands, whereas a parent in the 20 percent bracket gets back roughly 30 percent counting income tax and resident tax together.

If the child has a deferral under the student payment exemption, their future pension will be smaller unless the parent pays (this becomes final once the 10-year back payment window closes). The parent pays and the parent takes the deduction is the arrangement that loses neither pension entitlement nor tax. For how the exemption and back payment work, see National Pension exemptions and deferrals.

Back payment and advance payment: deduct it all in the year you pay, or split it

• Back payment (tsuinou) — premiums for periods under the student payment exemption or another exemption can be paid back within 10 years, and the amount paid becomes a social insurance premium deduction in the year of the back payment [Japan Pension Service]. From the third fiscal year after the fiscal year of approval onward, a surcharge is added, so the sooner you pay the cheaper it is. If a parent makes the back payment in a lump sum, the parent's deduction for that year jumps.
• Two-year advance payment — paying two years at once earns a discount. For the deduction you may choose either to deduct the whole amount in the year you pay or to split it across each year covered. Take the whole amount in a year when your income is high; if next year's rate will be the same, splitting makes no difference.
• Credit card and direct debit — paying from the parent's card or account makes it demonstrable that the parent paid. If the payment leaves the child's account, handing the child the money afterwards does not turn it into the parent's deduction.

Filling in the year-end adjustment: the social insurance premium deduction box

Company employees write, in the social insurance premium deduction section of the "Declaration of Insurance Premium Deductions for Employment Income Earner" used for the year-end adjustment, the type of premium, the payee, the name and relationship of the person liable for the premium, and the amount paid. For National Pension premiums you must attach or present a premium deduction certificate; for National Health Insurance premiums no certificate is required, but you still write in the amount [NTA No.1130].

For the year-end adjustment paperwork as a whole, see the year-end adjustment guide for company employees.

A parent's National Health Insurance and long-term care premiums: amounts withheld cannot be deducted

For a retired parent, National Health Insurance premiums, long-term care insurance premiums and medical care insurance for the elderly premiums are, as a rule, taken by deduction at source from pension (special collection) when the annual pension is 180,000 yen or more. Premiums withheld that way are the parent's own deduction and cannot be treated as paid by the child. Only amounts the child actually paid by payment slip or direct debit can go on the child's return.

If you want the child to be the payer, you have to apply to the municipality to switch from deduction at source to direct debit from the child's account. Long-term care insurance premiums are withheld as a rule and many municipalities do not allow the switch, so in practice this mostly applies to National Health Insurance and medical care insurance for the elderly premiums. For a parent living apart, keep records of your remittances so you can show that you share living expenses. For how that requirement is judged, see sending money to a parent living apart and the dependent deduction.

Whether you claim a parent as a tax dependent or add them to your health insurance also changes the premium burden itself. The full picture of the trade-offs is in whether it pays to claim a parent as a dependent.

Three points people get wrong

• You can claim it even if the person is not your dependent — the requirement for the social insurance premium deduction is sharing living expenses, and it has nothing to do with whether the person qualifies for the dependent deduction. Even if a child earns enough from a part-time job to fall outside the dependent deduction, National Pension premiums the parent paid are the parent's deduction.
• What the child paid cannot become the parent's deduction — "I gave them the money afterwards" does not work. Switch to the parent's account or card before the payment is made.
• No double counting — premiums the parent has deducted cannot also be deducted by the child on their own tax return. There is only one deduction certificate, and only one of you can use it.

Frequently asked questions

Summary

• If you pay the insurance premiums for a family member who shares your livelihood, the full amount becomes your own social insurance premium deduction.
• The national pension premium for FY2026 is 215,040 yen a year. If a parent in the 20% tax bracket pays it, that saves about 64,500 yen in tax; for a child with no income, the saving is zero.
• Back payments under the student payment exemption are also deducted in the year the back payment is made. Switch the account transfer or card payment to the parent's so the parent pays.
• The deduction certificate arrives in the child's name, but if the parent actually paid, it may be attached to the parent's tax return.
• National health insurance and long-term care insurance premiums withheld from a parent's pension are the parent's own deduction. Only amounts the child actually pays count toward the child's deduction.

Reference links (sources)

This article is based on the following materials. Premium amounts and forms change from year to year, so check the latest guidance.

• National Tax Agency No.1130, Social insurance premium deduction (premiums of relatives sharing living expenses; the full amount is deductible; a certificate must be attached for National Pension)
• Japan Pension Service, Back payment system for National Pension premiums (within 10 years; surcharge from the third fiscal year onward)
• Japan Pension Service, Student payment exemption (deferral) for National Pension
• National Tax Agency No.2260, Income tax rates

Note: this article provides general information and is not tax advice. The savings shown are approximate. For your own situation, check with your employer, the tax office or a tax accountant.