US taxes married to a Japanese citizen: the "NRA" box, when you need an ITIN, and when filing jointly backfires

The short version. If you’re a US citizen married to a Japanese national who isn’t a US person, you usually have three filing paths. Married Filing Separately (MFS) lets you write “NRA” in your spouse’s SSN box — no ITIN, no election, but you must paper-file. Married Filing Jointly (MFJ) needs a §6013(g) election, which forces an ITIN and pulls your Japanese spouse’s entire worldwide income onto your US return — and it’s a once-in-a-lifetime choice. If you have a qualifying child, Head of Household (HOH) often beats both. For most people with a working Japanese spouse, MFS is the path of least pain.

I’m Japanese, and my own US tax returns during my four years in the States were handled by a firm my company paid for — I filled in a questionnaire and signed. So I’m not writing this from “I did my own §6013(g) election.” I’m writing it because when I researched cross-border finances for my own move, this question came up constantly in the expat forums — and the advice was a mess. This is my research, laid out as a decision guide — not tax advice. Confirm every number against the IRS pages and a professional before you file.

The three filing statuses, side by side

Your spouse is a Japanese citizen who lives in Japan and has never been a US resident. That makes them a nonresident alien (NRA). As a US citizen you still have to file, and your choice of status drives both your paperwork and your tax bill.

Standard deduction figures are the Tax Year 2025 amounts (returns filed in 2026) after the One Big Beautiful Bill. Confirm against the IRS inflation-adjustment page before filing.

Path 1 — MFS with “NRA”: the simplest exit

This is the default for a reason. The 2025 Form 1040 instructions say plainly: if your spouse has neither an SSN nor an ITIN and isn’t required to have one, you enter “NRA” in the spouse’s SSN space and write their name. That’s it. Your Japanese spouse never touches the US tax system.

The catch: a return with “NRA” in that field can’t be e-filed — the IRS system demands a numeric identifier. You print it and mail it. Budget for an international-mail tracking option; a return that vanishes in transit near an April deadline is a headache measured in months, not dollars.

The math isn’t generous but it’s clean. MFS gets a $15,750 standard deduction — same as single — and MFS brackets are exactly half the MFJ thresholds. So if you’re the only earner, you get no “income-splitting” benefit. You’re trading tax efficiency for not dragging your spouse’s Japanese salary, dividends, and any rental income onto a US return. For a spouse with a real Japanese income, that trade is almost always worth it.

Choose MFS + “NRA” if: your spouse earns meaningful Japan-source income, you want zero exposure of their finances to the IRS, and you can live with paper filing.

Path 2 — MFJ via §6013(g): powerful, and a trap if you misuse it

IRC §6013(g) lets you elect to treat your NRA spouse as a US resident for income-tax purposes. You attach a signed statement from both spouses, your spouse gets an ITIN, and you file jointly with the $31,500 standard deduction and wider brackets.

Here’s what the deduction headline hides:

• Worldwide income. Once you elect, both spouses report their entire worldwide income — this year and every later year the election stands. Every yen of your spouse’s Japanese salary, interest, and dividends becomes reportable on the US return.
• Treaty benefits waived. While the election is in effect, your spouse can’t claim US–Japan treaty protections as a Japanese resident.
• Once-in-a-lifetime. If the election ever ends — revocation, separation, death, or IRS termination for bad records — you can’t make it again. Ever.
• PFIC and FBAR sludge. Pulling your spouse’s Japanese accounts and Japanese mutual funds into US visibility can trigger the PFIC regime, which is brutal on ordinary Japanese investment funds. If your spouse holds Japanese 投資信託, read how PFIC rules hit Japanese funds for US persons before you even consider this — it can turn a “bigger deduction” into a punitive-tax filing nightmare.

MFJ genuinely helps in one narrow case: you’re the sole earner, your spouse has little or no income, and there’s little foreign income to expose. Then the doubled deduction and wider brackets are real money. Outside that case, the election tends to cost more than it saves — and the once-in-a-lifetime nature means a bad election can’t be undone.

Choose MFJ via §6013(g) only if: you’re clearly the sole earner, your spouse has negligible income and no PFIC-type funds, and you’ve run the numbers with a professional. This is not a DIY decision.

Path 3 — Head of Household: the quiet winner when there’s a child

Most people don’t realize they might qualify. Under IRS Pub. 501, you’re “considered unmarried” for HOH purposes if your spouse was a nonresident alien at any point in the year and you did not make the §6013(g) election. That opens HOH — if you also have a qualifying person.

The key limit: your NRA spouse cannot be your qualifying person. You need someone else — typically a child or qualifying relative who lived with you more than half the year. Pub. 501 doesn’t carve out a special exception for a child living in Japan, so keep documentation of the living arrangement.

When it fits, HOH beats both other statuses: a $23,625 deduction ($7,875 more than MFS), better brackets than single/MFS, no worldwide-income exposure, no ITIN, no treaty waiver.

Choose HOH if: you have a qualifying child or dependent, you didn’t make a §6013(g) election, and you can document the household. For a US–Japan family with one primary earner and a kid, this is usually the answer.

What the wrong choice costs

The expensive mistake isn’t a missed deduction — it’s making an irreversible §6013(g) election to grab a bigger standard deduction, then finding out it exposed your spouse’s Japanese fund holdings to PFIC taxation you can’t walk back. That’s not a few hundred dollars; that’s years of complicated, higher-cost filings. The cheaper “mistake” — MFS’s smaller deduction plus paper filing — is a known, bounded cost you pay on purpose.

If your situation is anything beyond “MFS, NRA in the box, mail it,” this is worth paying a cross-border pro to model once. One place to start is Taxes for Expats, which handles NRA-spouse returns and §6013(g) elections routinely; that link gives $25 off your first filing. (Full disclosure: that’s a referral link — I get a small credit if you file through it. It’s one option among several, not the only one; compare before you commit.) Whatever you decide, this choice interacts with the rest of your first cross-border year — see the first tax year after leaving the US for how the pieces fit together.

FAQ

Do I really not need an ITIN to file separately?

Correct — for MFS, you write “NRA” in your spouse’s SSN field and their name, and file on paper. No ITIN, no W-7. You only need an ITIN if you go the MFJ/§6013(g) route, where the W-7 rides along with your paper return in the first year.

My spouse has NISA and Japanese mutual funds. Does that change things?

It’s a strong reason to avoid MFJ. A §6013(g) election makes your spouse’s worldwide holdings reportable, and Japanese funds are typically PFICs — punishing under US rules. If you’re a US person yourself, the same trap applies to your own accounts; see NISA and US citizens and keep the two spouses’ finances separate under MFS unless a professional says otherwise.

Can I switch statuses later?

MFS and HOH are decided year by year, so you can move between them as your situation changes. The §6013(g) election is the exception — once you end it, you can’t remake it — and that permanence shapes other decisions too, like whether to keep a US brokerage after moving to Japan. Treat it as permanent when you weigh it. Everything else in this is just paperwork.