SEISEI INSIGHTS — Succession
Who Can Investigate Assets, and When: The Line Between Life and Succession
2026-09-07
"My spouse is unwell and will not tell the family what he owns. Could you quietly find out for us now?" We receive this question from family members repeatedly.
The answer, stated first: while a person is alive, no third party can obtain their asset information without their consent. Not a spouse. Not a child.
During Life, Asset Information Belongs to the Individual
Where a living person's assets sit, and how much they hold, is that person's own information. Banks, brokerages, and insurers as a rule do not respond to enquiries from anyone other than the account holder. Presenting a family relationship does not change that treatment.
Using someone's identification or credentials without permission to check their holdings is not a planning technique at all; it creates a different category of legal problem. We do not advise anyone across that line.
Planning Needs Structure, Not Balances
Much of the anxiety here comes from overestimating the precision of information actually required. Succession design does not need balances to the yen. It needs a shape:
- How many properties, and in which countries or jurisdictions
- Whether financial accounts sit onshore or offshore
- Whether life insurance policies exist
- Whether foreign-situs assets are involved
With that much, the scope of taxation can be delineated and the structural questions identified. Design looks at how assets are positioned, not at transaction flows. And that outline is most reliably obtained the direct way: with the person's own cooperation.
After Succession Opens, Heirs Have Formal Routes
Article 896 of the Civil Code provides that "an heir succeeds, from the time of commencement of succession, to all rights and obligations attached to the property of the decedent, except those exclusively personal to the decedent." Once succession opens, heirs stand in the position of universal successors to the decedent's estate relations.
On that footing, the following routes operate in practice.
| Route | During life | After succession opens | Nature |
|---|---|---|---|
| Bank balance certificates and transaction histories | Not available without the person's consent | Obtainable as an heir | Each institution's succession procedures |
| Nayosechō consolidated property ledger | Not available | Requestable from the municipality as an heir | Municipal property-tax practice |
| Enquiry into the existence of life insurance policies | Not available | Via the Life Insurance Association's enquiry scheme | Industry body scheme |
| Building an outline through interview | Possible with the person's cooperation | — | The starting point of design |
An important qualification: these procedures are not uniformly prescribed by articles of the Civil Code or the tax statutes. They operate as institutional succession procedures, municipal administrative practice, and an industry association scheme. Requirements and documentation differ by institution.
Investigation Is a Right — and the Flip Side of an Obligation
Article 1-3 of the Inheritance Tax Act designates those who acquire property by inheritance or bequest as persons liable for inheritance tax, with categories drawn according to domicile, nationality, and related factors. An heir who bears that liability cannot discharge it without knowing what the decedent held.
Post-succession investigation, in other words, is not prying. It is conduct the system presupposes as the precondition of filing. What should become clear will become clear. The question is sequence.
Where We Stand
Explaining a boundary is not the same as pointing to a way around it. The opposite: identifying the route that is both legally sound and practically navigable is the most useful answer we can give an anxious family.
- During life, the workable range ends at building an outline with the person's cooperation.
- After succession opens, formal routes exist based on the heir's legal position.
- What design requires is not precision of balances, but the structure of how assets are held.
This article provides general information on tax systems and does not constitute individual tax consultation. Specific filings and tax computations are handled by licensed partner tax accountants whom we introduce.