Forced Heirship Claim Simulator | Did a Will or Gift Leave You Short of Your Reserved Portion?

Enter the estate value, the heirs involved, the claimant's relationship, and the amount they actually received, and this free simulator instantly calculates the forced heirship claim (Article 1046 of Japan's Civil Code).

The reserved portion (Article 1042 of Japan's Civil Code) is the minimum share of an estate guaranteed to statutory heirs other than siblings — that is, the spouse, children, and lineal ascendants (parents, grandparents, and so on). If a will or lifetime gift leaves an heir with less than that guaranteed share, the heir can bring a forced heirship claim (Article 1046) to recover the shortfall in cash.

Simulate from the estate value, the heirs involved, the claimant's relationship, and the amount actually received

What an infringement of the reserved portion is

Under Japanese law the reserved portion is **the minimum share guaranteed to statutory heirs other than siblings — the spouse, the children and the direct ascendants** (Civil Code art. 1042). Where a will or a lifetime gift leaves an heir with less than that, the shortfall can be recovered **in money**: that is the claim for infringement of the reserved portion (art. 1046). From the base estate, the composition of the heirs, the claimant’s relationship and what was actually received, this tool works out the reserved amount and the shortfall.

**The collective reserved portion is one half, or one third where only direct ascendants inherit.** Multiplying it by the claimant’s statutory share gives that person’s individual fraction. Note that this tool is **a simplified estimate that takes the base estate as a direct input**; in practice it is the estate at the opening of the succession, plus lifetime gifts within a defined range, less debts. Nor does it handle the order in which multiple legatees and donees bear the claim (art. 1047). For an exact figure, consult a lawyer.

How to use the simulator

Enter the base estate Give the estate on which the reserved portion is computed, in yen: the estate at the opening of the succession, plus lifetime gifts within the defined range, less debts.
Enter the composition of the heirs Whether there is a spouse, how many children, how many direct ascendants. With even one child, ascendants do not inherit, so a number entered for them does not enter the calculation.
Choose the claimant’s relationship Spouse, child or direct ascendant. Siblings hold no reserved portion and fall outside the tool.
Enter what was actually received Give the value the person in fact received, taking the will and any lifetime gifts into account.
Read the reserved amount and the shortfall You get the collective reserved portion, the statutory share, the individual fraction, the reserved amount, and the shortfall that can be claimed.

Tips for getting more out of it

A forced heirship claim is legally valid even if made verbally, but sending it by certified mail is recommended so there's a clear, documented start date for the statute of limitations.
The overall reserved portion is either one-half or one-third depending on who the heirs are, so check first whether lineal ascendants are the only heirs in your case.
If there's even one child, lineal ascendants aren't entitled to inherit, so entering a number of ascendants won't change the result.
A forced heirship claim isn't available to someone who renounced the inheritance, or who lost their inheritance rights through disqualification or disinheritance.

Where the simulator helps

When a will leaves you with what feels too little

Even a will giving everything to one child cannot cut below the reserved portion, and what falls short may be recoverable in money. This gives you the size of it.

When lifetime gifts were lopsided

Gifts within the defined range enter the base estate, so an infringement can arise even with no will at all.

When the person writing the will wants to check first

Seeing in advance whether a distribution cuts into anyone’s reserved portion makes a dispute among the heirs easier to avoid.

When you want to organise things before seeing a lawyer

Arriving with the composition of the heirs and an approximate shortfall gets the consultation to the substance sooner.

When more than one person must answer the claim

For how the burden divides among several legatees and donees, see the apportionment calculator; for building up the base estate itself, the base estate calculator.

Terms about the reserved portion

Reserved portion: The minimum share guaranteed to statutory heirs other than siblings (Civil Code art. 1042). A will cannot take it away.
Claim for infringement of the reserved portion: The right to claim the shortfall in money (art. 1046). The name, and its character as a monetary claim, date from the reform in force since July 2019.
Collective reserved portion: The share guaranteed to the heirs as a body: one half as a rule, one third where only direct ascendants inherit.
Individual fraction: The collective reserved portion multiplied by the claimant’s statutory share — that one person’s own fraction.
Base estate for the reserved portion: The estate at the opening of the succession, plus lifetime gifts within a defined range, less debts. The reserved amount is this multiplied by the individual fraction.
Direct ascendants: Parents, grandparents and other lineal relatives of earlier generations. They do not inherit where there is even one child.
Legacy: Property given to someone by will. In a claim for the reserved portion, a legacy bears the burden before any lifetime gift.
Extinctive prescription: The claim lapses one year from learning of the succession and of the gift or legacy that infringes, and in any event ten years from the opening of the succession (art. 1048).

Frequently Asked Questions

Yes. It expires one year after the claimant learns both that the inheritance has begun and that a gift or bequest infringes their reserved portion. Even without that knowledge, it's barred once ten years have passed since the inheritance began (Article 1048). It's important to assert the claim promptly.

No. The reserved portion is guaranteed only to the spouse, children (or their substitute heirs), and lineal ascendants — siblings aren't entitled to one at all (Article 1042, Paragraph 1). Even if a will leaves a sibling-heir with nothing, they can't bring a forced heirship claim.

Gifts to heirs generally count if made within 10 years before the inheritance began, and gifts to non-heirs generally count if made within 1 year before (Article 1044). Gifts that both parties knew would infringe the reserved portion count regardless of when they were made.

Start by notifying the person who received more than their share. A verbal claim is valid, but certified mail is commonly used to establish a clear record for the statute of limitations. If direct discussion doesn't resolve it, the next step is family court mediation, followed by a district court lawsuit if that also fails.

Side Note — Why the claim was renamed from a "reduction claim" to a "forced heirship claim"

Before Japan's Civil Code reform took effect in July 2019, this right was known as a "reduction claim." Under the old rules, when an heir whose reserved portion had been infringed brought a claim, the default outcome was "in-kind restitution" — the real estate or company shares that had been given away or bequeathed would end up co-owned between the claimant and the original recipient.

That co-ownership created real problems: selling the property, or exercising control over a company, now required the consent of every co-owner, which often caused serious trouble in business succession cases. So the 2019 reform consolidated the right into a purely monetary claim and renamed it the "forced heirship claim" to match.

Today the right is understood simply as a claim for cash, so the person on the receiving end doesn't have to give up real estate or company shares — they can resolve the claim by paying money instead. In exchange, the claimant no longer has a right to the property itself, but is guaranteed to be paid in cash.

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