Non-US Spouse US Tax Return: Your Filing Options from the UK

Non-US spouse US tax return: an introduction

A non-US spouse US tax return has three main routes. You can file as married filing separately, as head of household if you support a qualifying child, or jointly by electing to treat your spouse as a US resident. Separate filing keeps your spouse outside the US system. The joint election brings wider brackets and a bigger standard deduction. However, it also brings your spouse's worldwide income onto the return. Neither route is right for everyone, so the sensible step is to work out the figures both ways.

This article explains each option for Americans living in the UK. For the wider picture of how the two returns fit together, read our guide to US and UK tax returns prepared together. Our US federal returns service explains how we prepare the US side each year.

Why the non-US spouse US tax return question matters

The UK taxes each spouse alone. So marriage changes little on the UK side. The US is different. Your filing status sets your rates, your standard deduction and many of your reporting thresholds. Consequently, the choice you make on a non-US spouse US tax return affects almost every line. It also decides whether your spouse ever deals with the IRS at all.

What filing status do you use with a non-US spouse?

By default you file as married filing separately. If you pay more than half the cost of a home for a qualifying child, you may file as head of household instead. Alternatively, you and your spouse can choose to file jointly under a special election.

Married filing separately by default

Married filing separately is the default status. It applies to a married person who does not file jointly. Under section 6013 of the Internal Revenue Code, no joint return is allowed if either spouse was a nonresident alien during the year. Therefore, without the election, you file on your own. The IRS Publication 501 notes that tax rates are generally higher on a separate return. It also lists credits you lose, such as the education credits.

Your spouse's own income stays off your return. However, you still report your share of any joint income, such as interest on a joint savings account. Your spouse may not need a number at all. In that case, the Form 1040 instructions say you enter "NRA" where their SSN or ITIN would go.

Head of household with a qualifying child

Head of household is a status with wider brackets than a separate return. Normally a married person cannot use it. However, Publication 501 says you are considered unmarried for this purpose if your spouse was a nonresident alien at any time in the year. You still need a qualifying person, such as a child who lived with you. Importantly, your spouse is not a qualifying person for this test. Consequently, an American parent in the UK can often file as head of household while the British spouse stays outside the US system.

Married filing jointly by election

The joint option comes from section 6013(g). It lets a US citizen or resident and a nonresident spouse choose to treat the spouse as a US resident for the whole year. Both of you must agree. The IRS page on a nonresident alien spouse calls it a "once-in-a-lifetime choice". Section 6013(h) offers a similar election for a spouse who becomes a US resident during the year.

How does the section 6013(g) election work?

You attach a statement signed by both spouses to a joint return for the first year. From then on, your spouse is taxed as a US resident on worldwide income every year until the election is suspended or ends.

Making the election

The statement covers three points. First, it declares that one spouse was a nonresident and the other was not at year end. It confirms that you both choose to be treated as US residents for the whole year. It also gives each spouse's name, address and identification number. Usually you make the choice on the original joint return. However, you can also make it on an amended return, Form 1040-X. The limit is three years from filing or two years from paying the tax, whichever is later. If you do, you must amend any later returns too.

What the election brings in

Once the election applies, your spouse reports worldwide income on the joint return. That includes a UK salary, interest, dividends and gains. It also includes income the UK does not tax, such as ISA interest and ISA gains. For example, UK funds held in an ISA can be passive foreign investment companies for US purposes. Our article on PFICs and UK funds explains why that reporting can be heavy. Furthermore, you must file jointly for the first year, although later years can be joint or separate.

The election and the tax treaty

The election also limits treaty claims on a non-US spouse US tax return. The IRS says neither spouse can generally claim treaty benefits as a resident of a foreign country while the election is in effect. The regulation at 26 CFR 1.6013-6 gives an example of an electing spouse who stays taxable on worldwide income despite a treaty tie-breaker. There is a narrow exception for certain income under exceptions to the treaty's saving clause. Therefore, we test the treaty position before a couple elects, not after.

How does your choice change thresholds and credits?

The joint election roughly doubles your standard deduction and the lower bracket bands. However, it also brings your spouse's assets into Form 8938 and the spouse's taxes into your foreign tax credit. Each piece moves in a different direction.

Standard deduction and brackets

Start with the standard deduction. The IRS inflation adjustments for tax year 2026 set it at $16,100 for single and separate filers. It is $24,150 for head of household and $32,200 for a joint return. For tax year 2025 the same page gives $15,750, $23,625 and $31,500. The 24% bracket begins at $105,700 for a single filer in 2026 and at $211,400 on a joint return. Consequently, on a non-US spouse US tax return, a joint filing helps most when one spouse earns far more.

Form 8938 and the FBAR

The IRS page on whether you need Form 8938 sets thresholds for people living abroad. A separate filer reports above $200,000 at year end or $300,000 at any time. A joint return doubles these to $400,000 and $600,000. However, the Form 8938 instructions make an electing spouse a specified individual, so their assets count too. Our article on Form 8938 for Americans abroad covers the detail.

The FBAR works differently. An IRS practice unit on the FBAR says residence for FBAR purposes is decided without regard to the 6013(g) election. Therefore, an electing spouse is generally not required to file their own FBAR. You still report joint accounts in full on yours.

Foreign tax credit and the FEIE for both of you

The foreign tax credit is a credit for foreign income tax. You claim it on Form 1116. On a joint return, the UK tax your spouse pays can support credits against the US tax on their income. The foreign earned income exclusion, or FEIE, is an alternative that removes foreign wages from US tax up to a yearly limit. The IRS guide to figuring the exclusion says each spouse who qualifies can claim it separately. The limit is $130,000 per person for tax year 2025 and $132,900 for 2026. However, IRS Publication 54 says you cannot take a credit for foreign tax on wages you exclude.

The child tax credit

The child tax credit is worth up to $2,200 per qualifying child for 2025. According to the IRS child tax credit page, up to $1,700 of it is refundable. The full credit applies up to $200,000 of income, or $400,000 on a joint return. Each child needs a Social Security number valid for employment. The 2025 Schedule 8812 instructions add that on a joint return only one spouse needs a valid SSN, and the other may use an ITIN. Notably, the same instructions say that if you file Form 2555 for the FEIE, you cannot claim the refundable part. Consequently, the credit often pushes a non-US spouse US tax return towards the foreign tax credit.

Does your spouse need an ITIN or SSN?

Your spouse needs an SSN or an ITIN if you file jointly, or if they file a return of their own. On a separate return where neither applies, you write "NRA" instead.

When a number is needed

An ITIN is an Individual Taxpayer Identification Number. The IRS issues it to people who need a tax number but cannot get an SSN. The IRS ITIN page confirms that a nonresident spouse who files jointly with a US spouse can get one. A British spouse who has never lived or worked in the US is usually not eligible for an SSN. Therefore, the joint election normally means an ITIN application.

Applying on Form W-7

The application is made on Form W-7. The IRS says you include the tax return in the ITIN application package rather than filing it separately. It also says to allow seven weeks, or nine to eleven weeks in peak season or when applying from abroad. In practice, this means a non-US spouse US tax return filed jointly for the first time is usually a paper return. Therefore, we plan the timing around your filing deadline.

How does the UK side work?

The UK has no joint return. Each spouse files and pays on their own income, whichever US status you choose.

The UK taxes each of you separately

Your choice on a non-US spouse US tax return changes nothing for HMRC. Your spouse keeps their own personal allowance and their own Self Assessment, if they need one. However, the two systems still meet. For example, ISA income is tax-free in the UK but taxable in the US once your spouse elects in. Our article on the UK tax return for US citizens explains the UK side for the American spouse.

Marriage Allowance

Marriage Allowance is a UK relief. It lets a lower earner transfer part of their personal allowance to a spouse. According to GOV.UK on Marriage Allowance, the transfer is £1,260 and can cut the partner's tax by up to £252 a year. The lower earner must have income below the personal allowance, and the partner must pay basic-rate tax. It has no US effect, but we check it when preparing both returns.

Joint property and transfers between you

HMRC normally splits joint property income evenly. This applies to married couples who live together. A couple who own unequal shares can declare this using Form 17. Additionally, GOV.UK on gifts and Capital Gains Tax says transfers to a spouse you live with are usually free of that tax. The US view of a gift to a non-citizen spouse is different. Our article on a gift to a non-US spouse explains the annual limit.

Can you get out of the election?

Yes. Either spouse can revoke it, and it also ends on death, legal separation or for inadequate records. However, once it ends, neither of you can ever make it again.

Revoking the election

Under 26 CFR 1.6013-6, either spouse can revoke by signed statement. The revocation applies from the first year whose return due date has not yet passed. The statement is attached to the revoking spouse's return for that year, or filed with the IRS service centre if no return is due. It must be filed by that due date. Consequently, a couple who wants to stop for the 2026 year must act before the 2026 deadline.

Other ways it ends

The election also ends on death. Likewise, the regulation ends it under a decree of divorce or separate maintenance. The IRS can also end it if either spouse fails to keep adequate records. Separately, the IRS says the election is suspended for any year in which neither spouse is a US citizen or resident. That can matter if the American spouse later renounces.

Once in a lifetime

Section 6013(g)(6) makes a couple ineligible to elect again after it ends. Moreover, the IRS says neither spouse can make it later, even with a different spouse. Therefore, electing in for one good year and out again is rarely a sound pattern. In our experience, the cautious approach is to model several years ahead before the first joint non-US spouse US tax return is signed.

A worked example of a non-US spouse US tax return

Consider a typical case. Hannah is 38, a US citizen living in Manchester with her British husband, Tom. They have two children who are US citizens with Social Security numbers. Hannah earns a UK salary and Tom earns a smaller one. Tom also has a stocks and shares ISA invested in UK funds. This is an illustrative example, not a real client.

Filed without the election, Hannah's non-US spouse US tax return is head of household, because the children live with her and Tom is a nonresident. Tom stays outside the US system. Hannah claims the foreign tax credit rather than the FEIE, so the refundable child tax credit stays available. Her UK tax already covers most of her US tax on salary.

Next, we model the joint election. The joint standard deduction and wider bands help, and Tom's UK tax supports extra credits. However, Tom's ISA income becomes taxable in the US, and his UK funds bring PFIC reporting. He also needs an ITIN, and the election is effectively permanent. For Hannah and Tom, the separate route works out simpler and no more costly.

What Hannah's case shows

The answer turned on Tom's investments, not on the brackets. Had Tom had no income and no ISA, the joint return might have been better. Furthermore, the result can change as incomes and children's ages change. Therefore, we revisit a non-US spouse US tax return each year, while remembering that the election cannot be made twice.

How US UK Tax Experts can help

We prepare your US and UK returns from one file. As a result, the two agree. For a non-US spouse US tax return, we work out the separate, head of household and joint figures side by side. We look at credits, Form 8938, PFIC reporting and the treaty before anyone signs. If you choose the election, we prepare the statement and the ITIN application with the return. Our UK Self Assessment service covers the UK returns for both of you.

Conclusion

An American married to a non-US person has real choices. Married filing separately keeps the spouse out of the US system. Head of household often gives better rates where there is a qualifying child. The 6013(g) election gives the widest bands but brings the spouse's worldwide income and assets into US tax, and it can only be made once. On a non-US spouse US tax return, the safest course is to model each route before choosing.

Contact us

Need help with a non-US spouse US tax return? Email hello@usuktaxexperts.com or use our contact form. Tell us about both incomes, your children and any ISAs or pensions. We reply within one working day.