Combined Special Benefit & Contribution Share Calculator | Simulate Concrete Inheritance Shares in an Estate Division
Enter the total estate value along with each heir's special benefit amount and contribution share amount to instantly calculate the deemed estate, statutory share, and concrete share, accounting for both Civil Code Article 903 and Article 904-2 at once. A free simulator.
In a real estate division discussion, it is common for an heir who received lifetime gifts (a special benefit) and an heir who contributed to maintaining or growing the deceased's estate (a contribution share) to both be at issue at the same time. This tool calculates a single "deemed estate" that reflects both the advancement of special benefits (Civil Code Article 903, added to the estate) and the deduction of a contribution share (Civil Code Article 904-2, deducted from the estate), and estimates each heir's concrete share. If only one of these applies to your case, it is simpler to use the special benefit advancement calculator or the contribution share calculator on its own.
Simulate from the estate value, heir composition, special benefit amounts, and contribution amounts
Handling advancements and contributions together
In a real estate division conference it is common to find, within the same family, an heir who received a lifetime gift alongside an heir who supported the deceased through care or the family business and thereby helped preserve or increase the assets. The former is added back to the estate as an advancement under Article 903 of the Civil Code, while the latter is deducted from it as a contribution under Article 904-2 — two adjustments that pull in opposite directions and must be made at once.
This tool produces the deemed estate reflecting both at the same time and estimates each heir's actual share. The sequence is: add lifetime gifts counted as advancements to the estate (bequests are not added, as they are already part of it), deduct contributions to arrive at the deemed estate, multiply by each statutory share, then subtract each person's gifts and bequests and add back their contribution to reach the actual share. Where only one of the two situations applies, using the advancement calculator or the contribution calculator on its own is simpler.
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.
- 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
How to estimate the actual shares
- Enter the total value of the estate The combined value of the assets that actually exist at the start of the succession.
- Enter the composition of the heirs Specify how many of each there are among spouse, children and lineal ascendants (parents, etc.). The statutory shares follow from this.
- Enter each heir's lifetime gifts and bequests Enter lifetime gifts counted as special benefits and bequests separately. Gifts are added back to the estate; bequests are not, because they are already included in the total estate. Both are subtracted from the recipient's share. Leave them at zero for heirs to whom they do not apply.
- Enter each heir's contribution The addition for a special contribution to preserving or increasing the assets, such as providing care or working in the family business.
- Review the deemed estate and the actual shares After the additions and deductions, you see what each person actually receives.
Tips for getting more out of it
- If only special benefits or only a contribution share applies to your case, the dedicated single-purpose calculators (special benefit advancement, contribution share) have simpler input fields and are easier to follow.
- In practice, the common approach is to first add the lifetime gifts among the special benefits back to the estate (bequests are not added), then deduct the contribution share, to arrive at the "deemed estate." This tool automatically calculates in that order.
- An ascendant (parent, etc.) is not an heir if even one child is alive or has a substitute heir. Adding an ascendant row in that situation is automatically excluded from the calculation.
- A contribution share cannot exceed the value of the estate at the start of inheritance minus the value of bequests (Civil Code Art. 904-2(3)). This tool shows a warning if it does, but in practice the contribution amount itself needs to be revisited.
- If a non-heir relative, such as a child's spouse, contributed through nursing care, that falls under the "special contribution payment" (Civil Code Art. 1050) rather than a contribution share. Be careful not to confuse the two.
Where this helps
Care and lifetime gifts in the same family
Calculate in one pass the shares where one child cared for a parent and another received help buying a home.
Preparing for the division conference
Sharing the figures beforehand puts the starting point of the discussion on the arithmetic rather than on feelings.
Setting expectations ahead of mediation
Because the calculation follows how a family court reasons, it gives an indication of where matters may settle.
Weighing a claim to a contribution
Varying the contribution figure shows how far the shares move if the claim is accepted.
Estate division terms explained
- Advancement
- A bequest or lifetime gift received by an heir that counts as an advance on the inheritance. Lifetime gifts are added back to the estate; bequests are not, because they are already part of it. Both are subtracted from the recipient's share.
- Contribution
- The addition allowed to an heir who made a special contribution to preserving or increasing the deceased's assets. It is deducted from the estate.
- Deemed estate
- The notional value used as the basis for calculation: the estate plus lifetime gifts counted as advancements, less contributions. Bequests are not added, as they are already part of the estate.
- Statutory share
- The proportion the Civil Code allots to each heir. A spouse and children take one half each, for instance; the split varies with who the heirs are.
- Actual share
- What each person finally receives: the deemed estate times the statutory share, less their advancement and plus their contribution.
- Division conference
- The discussion in which all the heirs settle how the estate is divided. It requires everyone's agreement.
FAQ
Side Note — When special benefits and a contribution share become an issue at the same time
A special benefit (Civil Code Art. 903) and a contribution share (Civil Code Art. 904-2) are both adjustment systems aimed at achieving fairness in an estate division, but they run in exactly opposite directions. A special benefit is an addition-side adjustment that "reduces the share of someone who already received too much," while a contribution share is a deduction-side adjustment that "increases the share of someone who contributed a lot."
It is not unusual for both to be at issue at the same time in a real inheritance case. For example, an eldest son might have helped run the family business unpaid and contributed to maintaining the estate, while a younger son received a large lifetime gift as funds to buy a home. In this situation, a fair concrete share cannot be worked out unless both the eldest son's contribution share and the younger son's special benefit are reflected.
The common practice is to first add the lifetime gifts among the special benefits back to the estate (bequests are not added, as they are already part of it), then deduct the contribution share to arrive at a "deemed estate," calculate each heir's statutory share from that figure, and then subtract each heir's own special benefits (gifts and bequests) and add back their own contribution share. That said, this calculation order is not the only established method, and the factors a Family Court ruling weighs can vary from case to case.
An estate division where both special benefits and a contribution share are involved is also a classic scenario where heirs' claims tend to clash. An integrated simulation like this one is best used as a rough starting point for discussion, not a final answer.