Inheritance Tax Minor & Disability Deduction Simulator | Estimate Deductions and Tax Owed
Enter the total estate value, the statutory heir composition, and the age of the qualifying heir to estimate the deduction and tax owed under Japan's inheritance tax minor deduction (100,000 yen x (18 - age)) and disability deduction (100,000 yen, or 200,000 yen for severe disability, x (85 - age)).
When an heir is a minor or has a disability, a set amount can be subtracted from that heir's calculated inheritance tax (the total inheritance tax apportioned according to the share of the estate that heir actually acquires; this tool assumes the estate is acquired in line with the statutory shares). Any portion of the deduction that can't be used up can also be subtracted from the tax owed by that heir's dependent-support obligor (in practice, this is often one of the other heirs).
Minor and Disability Deduction Amounts
| Minor deduction | 100,000 yen x (18 years old - age at the start of the inheritance) - applies to inheritances on or after April 1, 2022 |
|---|---|
| Disability deduction (general disability) | 100,000 yen x (85 years old - age at the start of the inheritance) |
| Disability deduction (severe disability, tokubetsu shōgaisha) | 200,000 yen x (85 years old - age at the start of the inheritance) |
| When the deduction can't be used up | The unused portion can be subtracted from the tax owed by the qualifying heir's dependent-support obligor (Inheritance Tax Act, Article 19-3 and Article 19-4) |
The age used to calculate the deduction is the heir's age in full years at the start of the inheritance (the date the deceased passed away). Consult a tax accountant or tax office for the exact eligibility requirements and deduction amount.
Simulate From the Estate Value, Heir Composition, and Qualifying Heir's Age
What the Minor and Disability Deductions Are
The minor deduction and the disability deduction are reductions built into Japan's inheritance tax that let you subtract a set amount from the calculated inheritance tax of an heir who is a minor or has a disability. Because minors and people with disabilities will keep needing money for living expenses, education, or care for many years to come, the size of the deduction depends on the heir's age at the start of the inheritance: the minor deduction is a fixed amount multiplied by "the number of years remaining until age 18," while the disability deduction is a fixed amount multiplied by "the number of years remaining until age 85." If the qualifying heir's own tax isn't enough to absorb the full deduction, the leftover amount can still be subtracted from the tax owed by that heir's dependent-support obligor, as long as the obligor is also an heir in the same inheritance.
This simulator only asks for the total estate value, the statutory heir composition (whether there's a spouse and how many children there are), and the qualifying heir's age or disability category, then automatically works out the minor deduction amount, the disability deduction amount, their combined total, and the total inheritance tax before and after the deduction is applied. It also shows a breakdown of the tax owed by the qualifying heir and by the other heirs, so you can tell at a glance whether the deduction is fully absorbed by the heir's own tax or whether part of it needs to be shifted onto a dependent-support obligor instead.
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.
- Age thresholds and deduction amounts for the inheritance tax minor and disability deductions — National Tax Agency (国税庁) Effective from 2022-04 ／ Last checked 2026-09-19
- 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 Use the Minor and Disability Deduction Simulator
- Enter the total estate value Add up real estate, bank deposits, securities, and other assets to get the total estate value (the taxable base).
- Enter the statutory heir composition Select whether there is a spouse and how many children there are — these figures feed into the basic exemption and the total tax calculation.
- Choose the qualifying heir and their age Select the heir (child or spouse) you want to apply the minor or disability deduction to, and enter their age in full years at the start of the inheritance.
- Select the minor or disability category Check the minor deduction box if they're under 18, then indicate whether they have a disability and, if so, whether it's general or severe. Both boxes can be checked at once if both apply.
- Review the deduction amount and tax breakdown The combined minor and disability deduction total appears alongside the inheritance tax before and after the deduction, plus a breakdown by heir.
Tips for getting more out of it
- The minor deduction equals 100,000 yen multiplied by the number of years remaining until age 18, rounding any fraction of a year up (for example, 17 years and 3 months counts as 1 year).
- The disability deduction applies to heirs whose disability grade has been certified, for example via a physical disability certificate or a rehabilitation (therapeutic) certificate. Whether the heir qualifies as severely disabled doubles the deduction amount, so checking the certificate's grade beforehand improves the accuracy of the estimate.
- The minor deduction and the disability deduction can both apply to the same heir if the requirements are met (for example, a 15-year-old child with a disability can receive both deductions).
- To subtract an unused deduction from a dependent-support obligor, that obligor must also be an heir in the same inheritance.
Ways to Use the Minor and Disability Deduction Simulator
Estimating the tax burden when a minor child is among the heirs
When a minor child is among the heirs, you can see ahead of time how large a deduction they qualify for and roughly how much tax will actually be owed once it's applied.
Checking the effect of a disability certificate
When an heir holds a physical disability certificate or similar document with a certified grade, you can compare how the deduction amount changes between general disability and severe disability.
Preparing figures before consulting a tax accountant
You can try out several combinations of estate value and heir composition to have a rough estimate of the deduction and tax owed ready before meeting with a tax accountant.
Checking whether the deduction is fully absorbed or carried over
You can estimate whether the deduction amount exceeds the qualifying heir's own calculated tax, so you know in advance whether the difference will need to be subtracted from a dependent-support obligor's tax instead.
Minor and Disability Deduction Glossary
- Minor deduction (未成年者控除, Miseinensha Kōjo)
- A deduction that applies when an heir is under 18 at the start of the inheritance. It equals 100,000 yen multiplied by the number of years remaining until age 18.
- Disability deduction (障害者控除, Shōgaisha Kōjo)
- A deduction that applies when an heir has a disability. It equals 100,000 yen (200,000 yen for severe disability) multiplied by the number of years remaining until age 85.
- Severely disabled person (特別障害者, Tokubetsu Shōgaisha)
- Someone certified with an especially severe level of disability — for example, Grade 1 or 2 on a physical disability certificate, Grade 1 on a mental disability and welfare certificate, or an "A" (severe) rating on a rehabilitation certificate. Their deduction is double the amount for general disability.
- Dependent-support obligor (扶養義務者, Fuyō Gimusha)
- A person with a legal duty to support the qualifying heir, from whose tax any unused portion of the deduction can be subtracted instead. In practice, this is often another heir in the same inheritance.
- Calculated inheritance tax (算出相続税額, Sanshutsu Sōzokuzei-gaku)
- The amount that results from apportioning the total inheritance tax according to the share of assets each heir actually receives. The minor and disability deductions are subtracted from this figure.
- Age at the start of the inheritance (相続開始時の年齢)
- The heir's age in full years on the date the deceased passed away. This is the age used as the basis for calculating both deduction amounts.
Frequently Asked Questions
Side Note — Why the Formula Is "100,000 Yen x Number of Years"
Both the minor deduction and the disability deduction are structured so the deduction amount depends on "the number of years remaining until the heir reaches adulthood or old age." This reflects the fact that minors and people with disabilities will keep needing living, education, or care expenses well into the future, so the system sets aside part of the estate to cover that. The longer the remaining years (in other words, the younger the heir is at the start of the inheritance), the larger the deduction — a design built directly around this idea of "costs that will be needed later."
The disability deduction's cutoff age of 85 is said to reflect average life expectancy in the system's design. The twofold difference in the deduction amount between general disability and severe disability (tokubetsu shōgaisha) similarly reflects the idea that the level of care needed, and the constraints on daily life, scale with the severity of the disability.
The mechanism allowing an unused deduction to be subtracted from a dependent-support obligor's tax acts as a relief measure, ensuring the system's underlying purpose — securing future living support — holds up even when the minor or disabled heir's own inheritance tax is small (or they inherit almost nothing). However, this relief is only available if the dependent-support obligor is also an heir in the same inheritance, which makes it an important consideration when planning how to divide the estate.