By Dako
On paper, we’re the prepared couple. We have a trust. The wills are signed, and so are the powers of attorney. I’d filed “what happens if one of us dies” under handled, the way you file a fire extinguisher: present, inspected, hopefully never used.
Then I started reading about how Japan handles death, because our maybe-move keeps pulling every topic across the Pacific eventually. What I found wasn’t that our documents are wrong. They were written for one legal universe. Japan runs on another. If you’re the non-Japanese spouse in a household like ours, the differences aren’t trivia. They decide what your first month of grief would actually look like.
Two systems built on opposite assumptions
The American system treats death as a problem for a court. Your estate becomes a thing to be administered: probate opens, a personal representative gathers assets and pays debts, and only then does property reach the people you chose. The entire US estate-planning industry, trusts included, exists largely to route around that process.
Japan skips the courtroom by design. The Civil Code follows universal succession: at the moment of death, everything the deceased owned passes directly to the heirs. No probate, no administrator, no waiting for a judge. Sounds efficient, and it is. It’s also the part that surprises Americans most, because “everything” includes debts. Heirs inherit liabilities automatically, and the escape hatch is a formal renunciation filed with a family court, generally within three months of learning about the inheritance. Grieve, locate documents in a language you may not read, reconstruct someone’s finances, and decide. Three months.
There’s a quieter layer underneath: whose law applies at all. Japan’s conflict-of-laws statute says inheritance is governed by the deceased’s national law. If I die, Japanese law governs, wherever we live. If Jay dies while we’re living in Japan, US law nominally governs him, except that American conflict rules can point back to Japan for some assets, a bounce lawyers call renvoi. I’m not going to pretend I can trace every ricochet. The takeaway for a mixed-nationality couple is simpler and stranger: the two of us can be subject to different inheritance regimes while sharing one bed.
If your Japanese spouse dies first
Here’s the scenario I actually wrote this post for. Not my inheritance. Jay’s.
Start with the good news, because there is real good news. Nationality does not affect who counts as an heir under Japanese law. A non-Japanese spouse is a full statutory heir, no asterisk. The default shares are fixed by the Civil Code: a spouse inheriting alongside children splits the estate half and half, spouse alongside the deceased’s parents takes two-thirds, spouse alongside siblings takes three-quarters. If I die under Japanese law, Jay and our kids share everything, by right.
The bad news is everything between the right and the money.
Japanese banks freeze accounts when they learn of a death. Not when the city office records it, but when anyone tells the bank, and the freeze holds until the heirs act together. Unlocking it takes paperwork built around institutions foreigners don’t have: the koseki family register to prove who the heirs are, registered-seal certificates to prove who’s signing. A foreign heir substitutes affidavits, embassy signature certificates, birth and marriage certificates with Japanese translations, and then sometimes has to explain to a branch employee what an affidavit is. Jay has stood next to me in Japanese government offices before, and what that feels like when you can’t read the forms is its own story. Now imagine that errand, alone, while the three-month renunciation clock runs.
One document changes this picture more than any other: a valid will. With one, the surviving spouse’s paperwork burden drops sharply, because the will itself answers questions the bank would otherwise put to a stack of foreign documents. Japanese practitioners consistently point to a notarized Japanese will as the cleanest tool for anyone whose heirs would include a non-Japanese spouse. Foreign wills can be recognized too, if they follow the formalities of where they were made or of the testator’s nationality or residence. But “can be recognized” and “works smoothly at a bank counter” are different sentences.
Forced heirship, the part with no American equivalent
American law, for the most part, lets you leave your things to whomever you choose. Write the will, name your people, done. Japanese law starts from the opposite premise: close family holds a protected claim on your estate that your will cannot erase.
It’s called iryūbun, usually translated as the legally reserved portion. Spouses, children, and parents hold it. Siblings don’t. The protected slice is half of the heir’s statutory share, a third when only parents survive. Since a 2019 reform it works as a money claim rather than a claim on specific property, so an infringed heir can demand cash equal to their reserved value. And it isn’t automatic. The heir has to assert it within the legal window, or the will stands as written.
Read that again from the perspective of a cross-border couple, because it cuts both directions. It protects a non-Japanese spouse from being written out. It also limits what any will governed by Japanese law can do, including plans that made perfect sense in an American living room. An estate plan that says “everything to my spouse, then the kids” fits inside the reserved portions comfortably. A plan with more creative geometry might not.
What we’re doing about it, and what I’d tell you to do
I’ll be honest about where our confidence cracked, and it wasn’t the shares or the frozen accounts. It was our trust. Specifically, what Japan might think of it.
A US trust isn’t a familiar object in Japanese practice. There’s no statute squarely addressing foreign trusts, and while scholars argue Japan should recognize one, planners who work both countries keep saying the same practical thing. Banks and officials meet them with confusion, and assets in Japan are easier for heirs when held the Japanese way. Tax is blunter still. Japan looks through the arrangement at its economic substance, and can tax a beneficiary as if they’d received the assets outright, with the treatment shifting based on how the trust is built. The centerpiece of our American planning could arrive in Japan as a complication wearing a cape.
So the documents we were proud of are still good documents. They’re just drafts now. We always expected to revise them as life changed, and the reading behind this post confirmed that a real move would mean rewriting them with someone who practices in both systems, not adapting them from memory.
If you’re the non-Japanese spouse, here’s the short list I’d actually work through:
- Map which country’s law would govern each of you, today and after a move. Your nationality sets your own default, not your address.
- Keep US beneficiary designations current. Retirement accounts pass by contract, and we covered what mixed-nationality couples face there already.
- If Japan-side assets are in your future, price a Japanese notarial will now.
- Before moving, ask a cross-border professional one blunt question: what does Japan do with our trust?
One more thing belongs on your radar, even though it’s a tax topic and this post is about law. Japan taxes heirs, not estates, and its exclusions are a fraction of America’s: ¥30 million plus ¥6 million per statutory heir, against a US federal exemption in the millions of dollars. A generous spousal relief shields most surviving spouses, up to the larger of the statutory share or ¥160 million. Rates climb to 55 percent, and anyone inheriting who isn’t a spouse, child, or parent pays a 20 percent surcharge on top. How far that system reaches into US assets, and the ten-year rule that decides it, deserves a post of its own, and it’s coming.
My own family is part of why this stopped being abstract for me. I have family in Japan, which means some version of Japanese inheritance law will probably knock on our door someday no matter which country we’re living in. This isn’t a topic we get to skip by staying put.
FAQ
Can a non-Japanese spouse inherit property in Japan?
Yes, fully. Heir status under Japanese law doesn’t depend on nationality, and a legally married spouse is always an heir. The friction is procedural: proving heirship without a koseki, substituting affidavits and embassy signature certificates, and working every step in Japanese.
Does our American will or trust work in Japan?
Sometimes, partially, slowly. Japan can recognize foreign wills that meet the right formalities, but banks and offices handle them awkwardly, and a US trust faces both practical suspicion and look-through tax treatment. Most cross-border planners suggest a separate Japanese will for Japan-side assets rather than stretching one document across two systems.
If we live in the US and my spouse inherits from family in Japan, does the US care?
It can. Large gifts and inheritances from abroad come with US reporting duties even when no US tax is owed, on forms with unpleasant penalties. Form 3520 and its thresholds deserve a post of their own. It’s on our calendar.
This article is general information about US and Japanese inheritance law, not legal or tax advice. Succession, conflict-of-laws, and estate planning questions are fact-specific, and cross-border ones doubly so. Please work with qualified professionals in both countries before acting, and see our Disclaimer for details.