Being married to a non-US citizen leaves you with three filing routes: married filing separately, which is the default; a once-in-a-lifetime election to treat your spouse as a US resident; or head of household if a qualifying child lets you claim it. US expat tax returns usually turn on which one you pick.
The choice is not a formality. One route keeps your spouse's income and accounts entirely outside the US system; another pulls their worldwide income onto a US return permanently. Reversing it is not possible.
Married to a non-US citizen: the three routes compared
| Married filing separately | Section 6013(g) election | Head of household | |
|---|---|---|---|
| Spouse's income on your return | No | Yes, worldwide | No |
| Spouse needs an SSN or ITIN | Not necessarily | Yes | Not necessarily |
| Standard deduction | Separate rate | Joint rate | Higher than separate |
| Spouse's foreign accounts reportable | No | Yes | No |
| Spouse can claim treaty benefits | Yes | No, while the election stands | Yes |
| Reversible | Yes, year by year | Once ended, never available again | Yes, year by year |
The default: married filing separately
If you do nothing, you are a married person filing separately. Your non-citizen spouse is simply not part of the US tax system: their salary, their pension, their bank accounts and their investments stay outside it.
The price is a narrower set of brackets and a smaller standard deduction than a joint return, and some reliefs are restricted. Where your spouse has no SSN or ITIN, you enter "NRA" in the space for their identifying number rather than leaving it blank.
For most Americans in Britain married to a British spouse, this is the right answer. The foreign tax credit usually cancels the US tax anyway, and nothing is gained by exposing a spouse's UK income to US reporting.
The election to treat a spouse as a US resident
You can elect to treat a nonresident spouse as a US resident and file jointly. The IRS sets out the mechanics on its page for the nonresident alien spouse: a statement signed by both of you, attached to the first joint return, giving both names, addresses and identification numbers.
From then on, each spouse reports their entire worldwide income for that year and all later years, until the election is ended or suspended. Neither of you can then claim treaty benefits as a resident of a foreign country while it stands.
Once the election is ended — by revocation, death, legal separation or inadequate records — neither spouse can make it again in any later year. It is a once-in-a-lifetime choice, so treat it as permanent.
It makes sense in a narrow set of cases: where the non-citizen spouse has little or no income, where a joint return unlocks credits worth more than the cost, or where the couple plan to move to the United States anyway. It is rarely right where the spouse has substantial foreign income, a foreign business or foreign pensions.
What the election drags in
Making your spouse a US resident for income tax makes their financial life reportable too. Their foreign accounts count towards the FBAR and Form 8938 thresholds, their foreign funds fall under the PFIC rules, and an interest in a foreign company brings its own filings.
That is a permanent administrative change, and it is the reason most advisers start from separate filing. The comparison between the two information returns is in FBAR versus Form 8938, and the reporting framework sits under cross-border taxation.
Getting an ITIN
Where your spouse does need a number, it is Form W-7. The IRS explains on its ITIN page that the application is attached to the front of the tax return, with documents proving foreign status and identity, and that the SSN space is left blank for the applicant.
Allow time: the IRS asks for seven weeks, and nine to eleven weeks during filing season or for applicants overseas. Filing an extension is usually wiser than filing late while you wait.
Head of household
An American married to a nonresident alien may be able to file as head of household, which is better than separate rates, if they paid more than half the cost of keeping up a home for a qualifying child or other qualifying relative. A spouse who is a nonresident alien does not count as a qualifying person for this purpose.
It is worth checking where there are children with Social Security numbers, because the filing status sits alongside the credit issues covered in the child tax credit for Americans abroad.
Gifts and estates work differently too
The unlimited marital deduction that lets a US citizen pass assets to a spouse free of gift and estate tax does not apply where the recipient spouse is not a US citizen. A much larger annual exclusion applies to gifts to a non-citizen spouse instead, indexed each year, and estates often use a qualified domestic trust to defer the tax.
That makes joint accounts, a jointly owned home and large transfers between spouses worth planning rather than assuming, particularly where one spouse holds most of the wealth.
Tranzesta models both filing routes before the first return is filed, because one of them cannot be undone. Book a consultation if you are an American with a non-citizen spouse. The comparison of the domestic statuses is in married filing jointly versus separately.
Frequently Asked Questions
How do I file if my spouse is not a US citizen?
The default is married filing separately, which keeps your spouse's income and accounts outside the US system entirely. You can instead elect to treat them as a US resident and file jointly, or, if a qualifying child lets you, file as head of household. The separate route is the most common for Americans abroad.
Does my non-citizen spouse need an SSN or ITIN?
Not always. If you file separately and your spouse has no US income and is not claimed on your return, you can enter "NRA" in the space for their identifying number. A number is required if you make the election to treat them as a US resident, and an ITIN is obtained on Form W-7 attached to the return.
What happens if I elect to treat my spouse as a US resident?
Both spouses must report worldwide income for that year and all later years until the election ends, and neither can claim treaty benefits as a resident of a foreign country while it stands. Your spouse's foreign accounts and investments also become reportable under the US information return rules.
Can I undo the election later?
You can end it, but not repeat it. If the choice is revoked or ended by death, legal separation or inadequate records, neither spouse can make it again in any later tax year. That once-in-a-lifetime restriction is why the decision should be modelled over several years before it is made.
Can I file as head of household if I am married to a nonresident alien?
Possibly. An American married to a nonresident alien may qualify if they paid more than half the cost of keeping up a home for a qualifying child or other qualifying relative. The nonresident spouse themselves does not count as a qualifying person, so the status depends on having someone else who does.
Is there an estate tax problem with a non-citizen spouse?
Yes, because the unlimited marital deduction does not apply where the surviving spouse is not a US citizen. Lifetime gifts to a non-citizen spouse are covered by a much larger annual exclusion that is indexed each year, and estates commonly use a qualified domestic trust to defer the tax until distributions are made.
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