Married to a Briton: the filing status choice that follows

It is the status for a married person who files their own return rather than a joint one. Each spouse reports their own income. For Americans abroad it is usually the default, because a British spouse is not a US taxpayer.

The status is unremarkable inside the United States. It becomes distinctive abroad, since it keeps your spouse's affairs entirely outside the American system. That separation is often exactly what a mixed-nationality couple wants.

It does carry costs. Several credits and allowances narrow under this status, and the arithmetic differs from a joint filing in ways worth modelling rather than assuming.

One thing it does not do is make you single for tax purposes. Marriage still shapes the return, through the status itself and through the thresholds attached to it. The separation concerns whose income appears, not whether you are treated as married.

Because the tables set it that way, and it catches people out constantly. Publication 501 lists the income at which you must file by status. For married filing separately, at any age, the figure is $5.

Compare that with the single-filer threshold, which runs into five figures. So the usual reasoning of I earned too little to file simply does not transfer. A few pounds of British bank interest can technically put you over the line.

The practical reading is straightforward. If you are American, married to a non-American, and have any income at all, assume a return is due. Our guide to what changes when you file from the UK covers what that return then contains.

Yes, through an election. The IRS allows a couple to choose to treat the nonresident spouse as a US resident where, at the end of the tax year, one spouse is a US citizen or resident and the other is not. That choice opens the joint return.

The consequence is broad. Once the election is in effect, both of you are treated as US residents for federal income tax purposes for all tax years it covers. Your spouse's British salary, savings and investments enter the American calculation.

For a spouse with modest UK income, the trade can work. For one with a substantial British career, a pension pot and an investment portfolio, it usually does not. The official guidance on the nonresident spouse election sets out the mechanics.

Exposure they never had. A British spouse with no American connection is invisible to the IRS. After the election, their ISAs, their workplace pension and their share portfolio all sit inside a system that treats several of those wrappers unkindly.

Investment wrappers deserve particular thought. UK funds held by a US filer raise passive foreign investment company issues, which our piece on ISAs and the PFIC problem explains. An election can import that problem into a household that did not have it.

In our practice we see the election chosen for a single year's tax saving, then regretted when the wider reporting arrives. Model the whole picture, not just the headline bill.

There is a reporting dimension as well as a tax one. An electing spouse joins the account disclosure regimes, so their ordinary British current account can become reportable. For a couple who keep separate finances, that intrusion is often the deciding factor.

Almost certainly, yes. A return naming your spouse needs an identifying number for them, and a British citizen with no US work history will not have a Social Security number. The Individual Taxpayer Identification Number fills that gap.

You apply on Form W-7, usually alongside the return that needs it. The ITIN guidance explains the documentation, which typically means certified identity evidence rather than photocopies.

Start early, because the process takes time and the documents involved are ones your spouse may need meanwhile. Numbers also require periodic use to stay active, so an ITIN obtained once can lapse if years pass without a filing.

Renewals catch people out too. Numbers that go unused for a long stretch can become inactive, and a lapsed number surfaces at the worst moment, usually when a return is ready to file. Check the status before filing season rather than during it.

Run the comparison before the first return sets a pattern. The order below keeps it honest.

Model several years rather than one. This choice tends to persist, and its effects compound.

Take an illustrative example: an American teacher in Leeds married to a British engineer. She earns a modest salary. He earns considerably more, holds a workplace pension and keeps a stocks and shares ISA built up over a decade.

Filing separately, she reports her own income, claims credits for the UK tax she paid, and owes nothing. Her husband stays outside the American system entirely. His ISA raises no US questions, because he is not a US filer.

Electing to file jointly would change all of that. His income and his wrappers would join her return, and the ISA would need American analysis. The joint rates look attractive in isolation. The full picture rarely does.

Reverse their incomes and the analysis shifts again. Where the American spouse earns far more and the British one has almost nothing, the election can genuinely help. That is why the comparison has to run on your actual numbers rather than on a rule of thumb about which status wins.

Children are often where the separate-filing costs show up. Some credits reduce or disappear under this status, so a household with children should compare the versions carefully rather than defaulting.

The refundable side of the child credit has its own trap, which turns on how you claim relief rather than on your status alone. Our guide to the child tax credit abroad covers that interaction in detail.

Each child needs a Social Security number for the credit, which for children born in Britain means consular paperwork. Start it early, because that queue does not move for tax deadlines.

Dependants can also affect which status is available at all. Head of household has its own tests, and meeting them changes the arithmetic considerably. Check them properly rather than assuming a child in the household settles the question.

Largely as two individuals. Britain taxes people separately, so there is no joint return to align with and no equivalent election to make. Your spouse's Self Assessment position, if they have one, stands on its own.

That independence is useful. It means the American choice does not disturb the British filings, and the two systems can be handled in the right order without either waiting on the other.

Where you both have UK income, foreign tax credits still work off your own figures. Our guide to avoiding double taxation covers how those credits get claimed.

Marriage allowance and similar British reliefs follow their own eligibility rules, entirely unconnected to your American status. Check them on their own terms rather than assuming the two systems line up. They rarely do, and the amounts involved are worth the few minutes.

It can, where you still have ties to a US state. States set their own residency rules, and some follow your federal filing status while others do not. A state that still considers you resident may tax income the federal return already sheltered.

The mismatch matters most for people who moved abroad recently from a state with aggressive residency rules. Cutting those ties properly is a separate exercise from your federal position, and it deserves its own attention.

Where no state connection remains, the question falls away entirely. Most long-settled expatriates are in that position, which is one reason the state issue surprises people who have only recently arrived.

Everything, eventually. A spouse who naturalises or takes a green card joins the American system permanently, and the filing status question resolves itself into an ordinary joint or separate choice. Their British assets come with them.

That prospect is worth planning around before it happens. Restructuring investments while a spouse is still outside the system is straightforward. Doing it afterwards means dealing with wrappers that already carry American consequences.

Green cards deserve the same forethought. The card brings filing duties immediately, and after enough years it brings exit rules on the way out. Neither is a reason to avoid one, though both are reasons to decide with open eyes.

So if citizenship or residency is on the horizon for your spouse, treat the tax conversation as part of the immigration one. The two decisions interact more than most couples expect.

We model both versions of the return before anything is elected, through our US federal returns service. That includes the ITIN application, the credit comparison, and an honest view of what an election would import into your spouse's finances.

If you have recently married, or you are filing this way already and have never tested the alternative, send us the outline and we will run the comparison at a fixed fee agreed first. This article is general information, not personal tax advice; take advice on your own facts from a qualified US-UK adviser.