Marriage Allowance for an American married to a Brit

What Marriage Allowance does for a mixed US-UK couple

Marriage Allowance moves a fixed slice of one spouse's Personal Allowance to the other, so the receiving spouse pays less UK income tax. It is a UK relief only. The IRS does not recognise it, has no matching rule, and sees its effect only through the amount of UK tax each spouse ends up paying.

HMRC's page on Marriage Allowance (opens the official GOV.UK page in a new tab) sets the transferable amount each tax year and states the most it can save the receiving partner. The amount is the same whoever transfers, and it does not grow with income. The transferring spouse's own allowance falls by the same slice, which costs nothing if their income was below the allowance anyway and costs a little if their income sits just under it.

For a couple where both are British, that is the whole story. Where one spouse is a US citizen, the saving lands on two returns. The UK return records less tax for one spouse, or slightly more for the other, and the US return then credits UK tax paid. A relief that looks like a pure gain on the UK side can be partly given back on the US side, depending on which spouse receives it.

Who can transfer and who can receive the allowance

The couple must be married or in a civil partnership; living together is not enough. The transferring spouse must normally have income below the £12,570 allowance or pay no income tax at all. The receiving spouse must pay tax at the basic rate, or in Scotland at the starter, basic or intermediate rate, before the transfer.

Citizenship does not enter the test, so an American can be either the giver or the receiver. Residence matters only indirectly. HMRC says living abroad does not affect a claim provided the spouse still gets a Personal Allowance. A partner who is not UK resident has an allowance only in the categories HMRC lists for UK income of people living abroad (opens the official GOV.UK page in a new tab), which include British citizens and EEA nationals. Where an American spouse lives outside the UK, entitlement to the allowance has to be confirmed before anything else.

Two further points come from the same HMRC guidance. A spouse born before 6 April 1935 may do better with Married Couple's Allowance, and a couple cannot have both. Where either spouse has savings, dividends or benefits in kind as well as wages, HMRC suggests checking which spouse should claim before applying. That is common in mixed couples, since US interest and dividends often sit in the American's name.

• Married or in a civil partnership; living together does not qualify
• Transferring spouse: income below the Personal Allowance, or no income tax paid
• Receiving spouse: basic rate taxpayer, or starter, basic or intermediate rate in Scotland
• Both spouses entitled to a Personal Allowance, wherever they live
• Not combined with Married Couple's Allowance in the same year

How HMRC gives the allowance and how far it backdates

The lower earner applies, online or through their own Self Assessment return. HMRC then gives the receiving spouse the extra allowance through a changed tax code or when that spouse's return is processed. A successful claim runs from 6 April of the tax year and renews each year until someone cancels it.

Under PAYE, the receiving spouse's tax code ends in M and the transferring spouse's in N. Where both file Self Assessment, the transferring spouse completes the Marriage Allowance section of their SA100 and the receiving spouse leaves it blank. HMRC asks the transferring spouse to file at least three days before the receiving spouse. A spouse whose code already ends in N or M need not fill in the section again, because the transfer carries forward.

Earlier years can be claimed too. HMRC's guidance currently allows a backdated claim to 6 April 2022 for any year in which the couple qualified, made by post rather than online. A backdated claim reduces the receiving spouse's tax for those earlier years at the allowance that applied in each. For an American receiver, that reduction in past UK tax is where the US side needs most care, as the next sections explain. Our UK Self Assessment service handles the claim and the return entries together.

How Marriage Allowance changes the US foreign tax credit

Marriage Allowance has no US counterpart, so the US return never sees the transfer itself. It sees the UK tax. An American who receives the allowance pays less UK tax on their own income, which leaves less to credit on Form 1116. An American who transfers it may pay slightly more UK tax, which can mean more to credit.

The US citizen still chooses a US filing status on the usual rules. Most use married filing separately, with a gross income filing threshold of $5, and report only their own income. Publication 54 (opens the official IRS page in a new tab) explains the alternative: the couple can elect to treat the British spouse as a US resident and file jointly, after which the spouse's worldwide income is taxed in the US for every year the choice stands. Publication 519 (opens the official IRS page in a new tab) sets out how that election is made and ended. Marriage Allowance does not change which option is open.

The credit is measured on UK tax actually owed. The Form 1116 instructions (opens the official IRS page in a new tab) deny credit for foreign tax that is not legally owed, including amounts the foreign country will refund, and say a later refund of credited tax requires an amended return reducing the credit. A backdated Marriage Allowance claim that cuts an American receiver's UK tax for earlier years is a refund of that kind. Each US return that credited the original UK tax for those years may then need a Form 1040-X, as our post on amending a US return from the UK describes.

Whether the lower UK tax costs anything in the US depends on the gap between the two liabilities. Where UK tax on the salary still exceeds the US tax on it, the credit wipes out the US tax either way and the loss falls on unused credits carried back one year and forward ten. Where UK tax drops below the US figure, some US tax becomes payable. An American excluding the salary under Form 2555 claims no credit on it, so the change makes no US difference to that income.

Which spouse should transfer: a decision table

The answer usually follows the income, because only the lower earner can transfer. What the table adds is the US consequence of each arrangement. It is our own summary, built from the HMRC eligibility rules and the Form 1116 instructions, and it assumes the American files married filing separately unless the joint election is noted.

The pattern across the rows is simple. The UK saving is fixed and certain. The US cost, where there is one, appears only when the American is the receiver and their UK tax falls below the US tax on the same income. Our Form 1116 guide explains the credit categories, and our cross-border tax service models both returns before a claim is made.

• British spouse transfers, American receives: the American's UK tax falls; the Form 1116 credit falls by the same amount; usually only excess credits are lost
• American transfers, British spouse receives: the spouse's UK tax falls; the American's US return is generally unaffected, apart from any small UK tax on their own income
• Joint election in force: both spouses' UK tax is on the joint return, so the household's creditable UK tax falls by the saving
• American excludes the salary on Form 2555: no credit is claimed on that salary, so the transfer changes nothing on that income
• Backdated claim with an American receiver: earlier UK tax is refunded, and the matching US credits may need reducing by amendment
• Verdict: claim it in most cases, but where the American receives it, check the US credit first and plan for any amended returns

A worked example of Marriage Allowance across both returns

Take a US citizen employed in Leeds on a basic-rate salary under PAYE, married to a British wife who left paid work to care for their children and has no income. She transfers part of her allowance to him. His code changes to end in M, and his UK tax for the year drops by the fixed amount.

On his US return, filed married filing separately, the UK tax on his salary is lower than before, so the foreign tax credit is lower. If his UK tax was well above the US tax on the salary, the US bill stays at nil and the cost is a smaller carryover. If the two were close, he may now owe a little US tax. His wife's position does not appear on his return at all, and she needs no taxpayer number, as our post on an ITIN for your British spouse explains.

Suppose they also backdate the claim. His UK tax for those earlier years is reduced at the allowance that applied in each. Every Form 1040 for those years that credited the original UK tax now overstates the credit, so each is reviewed and amended where the change alters US tax. Reverse the roles, with an American wife earning below the allowance and a British husband receiving it, and the US return barely moves. Our individual tax returns work prepares both sides from one set of figures, and the guide for Americans in the UK sets this alongside the other family rules.