Japan–US Cross-Border Inheritance — Tax, Probate, and Bank Accounts

When a Japanese national dies in the United States holding assets in both countries, the estate straddles two legal systems that do not communicate with each other, use different heir-identification mechanisms, and impose independent tax deadlines. The family runs two parallel tracks — US probate (or small estate affidavit) for American assets and Japanese inheritance procedures for everything else — and the 10-month Japanese inheritance tax deadline governs the pace of both.

The 10-Month Deadline That Drives Everything

Japan's inheritance tax (souzokuzei) must be filed and paid within 10 months of the date of death. This deadline is absolute. It does not pause while US probate works its way through county court, while bank accounts are being valued, or while the family searches for assets.

For a Japanese national — regardless of how long they lived in the US or where their heirs reside — the entire global estate is subject to Japanese inheritance tax. Every US bank account, every US real estate holding, every investment account, alongside every Japanese asset, falls within scope.

The basic exemption below which no filing is required:

JPY 30 million + (JPY 6 million × number of statutory heirs)

For a family with a surviving spouse and two adult children (three statutory heirs), the exemption is JPY 48 million. If the combined global estate exceeds this threshold, a return must be filed even if the spousal deduction eliminates the actual tax owed.

Japanese Bank Account Freezes

Japanese banks freeze accounts the moment they learn of the account holder's death — even informally. A phone call from a family member, a newspaper obituary, or a notice from the ward office triggers the freeze. Ordinary withdrawals are restricted while the formal estate division process is completed, although the statutory relief valve below allows a limited withdrawal under its conditions.

Full unfreezing requires a complete koseki paper trail (the decedent's koseki tohon, joseki tohon, and kaiseigenkoseki spanning birth to death), identification of all statutory heirs, a signed Agreement on Division of Inheritance (Isan Bunkatsu Kyogisho), and registered personal seals (inkan) from every heir. For heirs living outside Japan who do not have registered seals, Japanese banks accept a notarized Signature Certificate (Sign Shomei) issued by a Japanese consulate.

The 2019 relief valve: Recognizing that assembling these documents takes months, Japanese law allows a statutory heir to withdraw up to one-third of a deposit account balance, capped at JPY 1.5 million per financial institution, for urgent expenses (hospital bills, funeral costs) without the other heirs' consent. The withdrawing heir needs the current koseki showing their relationship, the decedent's koseki showing the death, and their own inkan shomeisho.

US Assets: Small Estate Affidavit or Probate

If the decedent held bank accounts, investment accounts, or other financial assets in the US, those assets are governed by state law. US institutions cannot read a koseki and will not release funds based on Japanese heir-identification documents alone.

Small estate affidavit (simplified path): Many states allow heirs to collect personal property using a sworn affidavit if the estate falls below a threshold:

• California: personal property under $184,500 (for deaths on or after April 1, 2025). A mandatory 40-day waiting period from the date of death applies before the affidavit can be presented to the financial institution.
• New York: personal property under $50,000 under the Surrogate's Court Procedure Act. A surviving spouse may collect up to $30,000 immediately; other relatives face a 30-day or six-month waiting period.

Ancillary probate (full court path): If US assets exceed the small-estate threshold or include real estate, the family must initiate probate in the US county court where the property is located. This requires hiring a US probate attorney; timing depends on the state and court.

Double Taxation and the Japan-US Treaty

US assets may be subject to both US federal estate tax and Japanese inheritance tax. The US estate tax applies to "US-situs" property (real estate, tangible property in the US, and certain financial assets) for non-resident decedents. The current US federal estate tax exemption is high enough that most estates are unaffected, but state-level estate or inheritance taxes in states like New York, Massachusetts, or Oregon have lower thresholds.

To prevent true double taxation, heirs can claim a foreign tax credit under the Japan-US Estate and Gift Tax Treaty. If US estate or inheritance tax was paid on US-situs assets, that amount can offset the Japanese inheritance tax on those same assets. The mechanics require coordination between a US estate attorney and a Japanese certified tax accountant (zeirishi).

Proving Heir Status Across Both Systems

This is the practical friction point. Japanese institutions prove heir status through the koseki. US institutions prove it through court orders (letters testamentary, letters of administration) or, for small estates, sworn affidavits.

Neither system recognizes the other's documents natively. The family needs:

• For US institutions: An English translation of the koseki showing the heir's relationship to the deceased, notarized if the institution requires it. Some US banks also require a death certificate and a Small Estate Affidavit or court-issued letters of administration.
• For Japanese institutions: The apostilled US death certificate with Japanese translation, the complete birth-to-death koseki chain, the Isan Bunkatsu Kyogisho (inheritance division agreement), and seal or signature certificates from every heir.

Families should prepare both sets of documents simultaneously rather than sequentially. Waiting for the US probate to conclude before addressing the Japanese side risks missing the 10-month inheritance tax deadline.

What the Guide Covers

The Japanese Dies in the US — Family Emergency Guide walks through both the US and Japanese inheritance tracks in parallel — the bank freeze and relief valve procedure, the koseki compilation process, the Small Estate Affidavit mechanics for California and New York, the inheritance tax calculation with the basic exemption formula, and the document checklist for proving heir status in both countries.