Japanese Special Contribution Payment Inheritance Tax Simulator | How Much Tax on a Caregiving Claim?
Enter the total estate value, the composition of statutory heirs, and the special contribution payment amount to estimate the inheritance tax owed by the contributor (with the 20% surcharge where it applies) and the adjustment to the paying heirs' taxable estate.
When a relative who is not a statutory heir (typically a child's spouse) has provided unpaid care or other contributions to the decedent, they can claim monetary compensation from the heirs under Japan's special contribution payment system (Article 1050 of the Civil Code, introduced in a 2019 reform). For tax purposes, this payment is treated as a bequest from the decedent, so the contributor owes inheritance tax on it (Article 4, Paragraph 2 of the Inheritance Tax Act). Whether the 20% surcharge (Article 18(1) of the Inheritance Tax Act) applies depends on the relationship to the decedent, not on heir status: it applies to everyone except first-degree blood relatives and the spouse. Typical contributors such as a child's spouse (a first-degree relative by marriage), grandchildren, siblings, nephews and nieces are surcharged, but a parent of the decedent who is not an heir because the decedent has children (a first-degree blood relative) is not.
Run a Simulation from the Estate, Heir Composition, and the Contribution Amount
What a special contribution payment is
It is far from rare for the person who bore years of caring for the deceased to be a relative who is not an heir — most often a child's spouse. Under the older law such a person could devote themselves entirely and still receive nothing from the estate. The special contribution payment, introduced by the 2019 reform of the Japanese Civil Code (Article 1050), lets them claim money from the heirs.
The tax treatment deserves care. The payment is deemed a bequest from the deceased (Inheritance Tax Act, Article 4(2)), so inheritance tax falls on the claimant. And most claimants fall within the twenty per cent surcharge under Article 18(1). Only first-degree blood relatives and the spouse are excluded, so a child's spouse (a first-degree relative by marriage), grandchildren and siblings are surcharged, while a parent who is not an heir (a first-degree blood relative) is not. The heirs who pay, for their part, may deduct what they paid from their own taxable value. Enter the estate total, the composition of the heirs and the amount of the payment, and this tool works out both sides at once.
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.
- 20% surcharge on inheritance tax (who it applies to and the rate) — National Tax Agency (国税庁) Effective from 2003-04 ／ Last checked 2026-09-18
- Statutory shares of inheritance and the share of a special beneficiary (Civil Code arts. 900, 903) — e-Gov Law Search (Digital Agency, Japan) Effective from 2019-07 ／ Last checked 2026-09-18
- Japanese inheritance tax rate table and basic exemption amount — National Tax Agency (国税庁) Effective from 2015-01 ／ Last checked 2026-09-17
How to estimate the tax
- Enter the total value of the estate The combined taxable value. Use the figure before the special contribution payment is deducted.
- Enter the composition of the statutory heirs Specify whether there is a spouse and how many children. The basic deduction and the apportionment of tax follow from this.
- Enter the amount of the payment The sum being claimed, or claimed from you.
- Check the claimant's tax If the surcharge applies, the inheritance tax after the twenty per cent surcharge is shown. If the contributor is a parent of the decedent (a first-degree blood relative), tick the checkbox to calculate without the surcharge.
- Look at the paying side too You also see how far the heirs' own taxable value falls.
Tips for getting more out of it
- If the parties cannot agree on the special contribution payment, the contributor can ask the family court for a ruling in lieu of an agreement. That request must be made both within 6 months of learning of the start of the inheritance and of the heirs, and within 1 year of the start of the inheritance (Article 1050, Paragraph 2 of the Civil Code); the right is lost as soon as either period passes, so it is best to start discussions early.
- Because an heir who pays the special contribution payment can deduct that amount from their own taxable estate, the total tax burden across everyone involved stays roughly the same — the payment mainly shifts how the burden is split between the contributor and the heirs.
- Before the 2019 Civil Code reform, a child's spouse could provide years of devoted caregiving but had no way to claim anything, since only statutory heirs could benefit from the older "contribution share" system. The special contribution payment is a relatively new system created to correct this unfairness.
- Since the amount is set through negotiation between the parties, it's worth entering it into this tool once it's finalized to get a rough sense of the tax burden before filing.
Where this helps
A son- or daughter-in-law who provided care and is weighing a claim
What you keep is not the sum claimed: you have to work from the figure after the surcharged tax is taken off.
Anticipating a claim against you
Because what you pay is deductible from your taxable value, you can check how your own burden shifts.
Organising the issues before the division conference
A special contribution payment moves every heir's tax, so sharing the figures early is worth the effort.
Comparing with a provision by will
Had the deceased arranged a bequest during their life, no claim would have been needed at all; this gives you the comparison.
Special contribution terms explained
- Special contribution payment
- Money that a relative who is not an heir may claim from the heirs after contributing without payment to the deceased's care (Civil Code, Article 1050).
- Special contributor
- The person entitled to make the claim. Whether the twenty per cent surcharge applies depends on their relationship to the deceased, not on heir status: a child's spouse, grandchildren and siblings are surcharged, while a parent of the deceased (a first-degree blood relative) is not.
- Twenty per cent surcharge
- The rule multiplying inheritance tax by 1.2 where someone other than a first-degree blood relative of the deceased (a child or parent) or the spouse acquires property by inheritance or bequest (Inheritance Tax Act, Article 18(1)). An adopted grandchild who is not inheriting by representation is also surcharged.
- Deemed bequest
- Treating something as a bequest for tax purposes although it is not one in fact. A special contribution payment is treated this way.
- Taxable value
- The value of the property each person acquires. A special contribution payment made is deducted from it.
- Basic deduction
- 30 million yen plus 6 million yen per statutory heir. A special contributor is not counted among the statutory heirs.
Frequently Asked Questions
Side Note — What's the Difference Between "Contribution Share" and "Special Contribution Payment"?
Japanese inheritance practice has long recognized a "contribution share" (kiyobun) for heirs who made a special contribution to maintaining or increasing the decedent's assets. The catch was that only statutory heirs could claim it — so if a son's wife spent years caring for her parents-in-law, she herself, not being an heir, had no way to claim anything for it, a gap that was widely seen as unfair.
The special contribution payment, introduced in a Civil Code reform that took effect in July 2019, addresses this by giving relatives who are not statutory heirs a monetary claim of their own. It is available to blood relatives within the sixth degree, spouses, and relatives by marriage within the third degree — unmarried partners and friends are not eligible. The claim is limited to cases of unpaid care or similar labor that specifically contributed to maintaining or increasing the decedent's assets; simply living together or doing ordinary household chores usually isn't enough.
Another notable feature is how it's handled for tax purposes: the payment is treated as a "bequest," even though it's legally a claim under the Civil Code rather than something left by will. This fiction exists mainly to make sure the payment doesn't slip through the cracks of the inheritance tax system. As a result, the contributor occupies a somewhat unusual position — they're never counted toward the basic deduction's heir count, yet the 20% surcharge is decided for them by relationship, just as for any other beneficiary (it applies to everyone except first-degree blood relatives and the spouse). A parent is not surcharged even without being an heir, while a child's spouse is.