Introduction: Why the Affidavit of Support Is a Tax Problem First
The affidavit of support is the document that decides whether an American in Britain can take a British husband or wife home, and it runs on US tax returns. Most families treat the affidavit of support, Form I-864, as immigration paperwork. However, three of its hardest questions are tax questions. The form asks for your total income from your federal return. It asks where you are domiciled. Finally, it asks you to sign a contract that can outlast the marriage.
For a wealthy American in London, income is rarely the obstacle. Instead, the obstacle is the paper trail. Many high earners have missed US tax returns for years because UK tax always exceeded the US bill. Others filed correctly but chose the exclusion that shrinks the one figure the consular officer reads. Furthermore, several have described their life in Britain to the IRS in words that contradict what they now tell the embassy.
This guide explains each of those collisions with current 2026 figures. Additionally, it covers the points the immigration guides leave out: which filing method protects your affidavit of support, which UK assets count, and what the move costs on both sides of the Atlantic. TaxYork prepares the US and UK returns that sit behind these applications, so the focus here is the tax file.
What the Affidavit of Support Requires From a Sponsor Abroad
The affidavit of support in plain terms
An affidavit of support is a legally binding contract between you and the US government. You promise to keep the sponsored immigrant at or above 125% of the federal poverty guidelines. Congress created it in section 213A of the Immigration and Nationality Act, and the detailed rules sit in 8 CFR 213a.2. Every spouse of a US citizen applying for an immigrant visa needs one. Consequently, no British spouse receives an IR-1 or CR-1 visa at the London embassy without it.
The petitioner must sign an affidavit of support, whatever their wealth. A joint sponsor can add income, but nobody can replace you as the primary sponsor. Therefore, your own tax record and your own domicile are tested in every case. The current Form I-864 page carries the form, and the instructions were reissued with an edition date of 24 August 2026.
The 2026 income floor
The income test in the affidavit of support is modest by London standards. The 2026 poverty guidelines on Form I-864P took effect on 1 March 2026. For the 48 contiguous states, 125% of the guideline is $27,050 for a household of two, $34,150 for three, $41,250 for four and $48,350 for five. Your household includes you, your spouse, your dependants and anyone you sponsored earlier.
A banker or company owner clears those figures many times over. Nevertheless, the test is not what you earn. The test is what your federal return shows, and whether that income will follow you to America. Those two conditions cause almost every refusal we see among high earners.
Three things the officer checks
The consular officer reviews three items in every affidavit of support. First comes the federal return for the most recent tax year. Next comes proof of current income that will continue after the move. Finally comes your domicile. Each item has a tax dimension, and a weakness in one cannot be cured by strength in another. For example, $5 million of liquid assets does not repair a missing return.
The US Tax Returns Behind the Form
Which returns the affidavit of support needs
For an affidavit of support, you must supply an IRS transcript or a photocopy of your federal individual return for the most recent tax year, counted from the date you sign. The regulation makes one year mandatory. However, the form has lines for three years of total income, and you may submit all three if they help. In practice, most London cases go in with three years, because a single year invites questions about the other two.
In practice, transcripts are the cleaner evidence. You can request them through the IRS Get Transcript service or on Form 4506-T. If you send photocopies instead, you must attach every Form W-2 and Form 1099 that relates to them. Moreover, the instructions tell you not to send state returns, and not to send foreign returns unless you claim you had no US filing duty.
Missed US tax returns stop the affidavit of support
The instructions leave no room for doubt on missed US tax returns. If you were required to file for a year and did not, you must file all late returns with the IRS first. Then you attach the transcript or a copy of the late return. The regulation goes further. An affidavit of support from a sponsor who should have filed and did not is treated as insufficient, unless the sponsor proves there was no duty to file.
Living in Britain is not that proof. The instructions state that residence outside the United States does not exempt US citizens from filing. Furthermore, the filing threshold is lower than most people expect. An American married to a non-American usually files as married filing separately, and that status carries a gross income threshold of just $5. Therefore, almost every American in Britain with a British spouse had a filing duty in every year of the marriage.
How late returns reach the embassy
However, late returns take time to appear on a transcript. Paper returns in particular can take months to process. Consequently, the tax catch-up should start before the immigrant petition, not after the embassy asks for documents. A sponsor who files three late returns the week before the interview arrives with photocopies and no transcript, which invites an administrative delay.
Additionally, the catch-up has to be done properly. Late returns usually bring late foreign account reports with them, since UK current accounts, ISAs and pensions often exceed the $10,000 aggregate threshold for the FBAR. For non-wilful cases, the IRS streamlined procedures remain the standard route, and our IRS Streamlined Filing service handles that work. Additionally, serious tax debt can block the trip itself, as our guide to IRS passport revocation for tax debt explains.
Total Income: The Line That Catches Americans in Britain
Why the exclusion can show zero income
For the affidavit of support, the officer looks at the total income line on Form 1040. That is line 9 on the current Form 1040. Importantly, the foreign earned income exclusion is deducted before that line. The exclusion claimed on Form 2555 flows through Schedule 1 as a negative figure and reduces total income.
Specifically, the exclusion is $130,000 for 2025 and $132,900 for 2026. As a result, an American earning £95,000 in London, roughly $125,000, can file a perfectly correct return that shows total income of zero. The tax bill is nil, and so is the figure on the affidavit of support. The officer then sees a sponsor with no income on paper.
Why the foreign tax credit protects your affidavit of support
The foreign tax credit works differently. It reduces the tax, not the income. Therefore, a return that uses the credit shows the full salary on line 9, and UK income tax then wipes out the US liability lower down. For a higher or additional rate taxpayer in Britain, the credit normally produces the same nil bill and leaves excess credits to carry forward.
For high earners the gap is narrower but still real. A director on £420,000 shows about $553,000 with the credit and about $423,000 with the exclusion. Both figures clear the floor. However, the choice still matters, because Form 2555 carries a second risk that has nothing to do with income. We return to it under domicile below. Our US tax return preparation for expats weighs both methods each year.
Income that will not follow you home
Nevertheless, a strong return is still only history. The officer wants current income that will continue from the same source after you move. A London salary that ends on the day you resign is not continuing income. Consequently, a sponsor with a $550,000 return can still be treated as having no qualifying income at the interview.
Fortunately, there are three ways through. A signed US employment contract or offer letter shows income that starts on arrival. Investment income, such as dividends and rents, continues wherever you live. Alternatively, assets can carry the whole case. Notably, your spouse's income can count as well, wherever they live now, provided it continues from the same source after they become a permanent resident. A British spouse with UK rental income or a portable remote role can therefore help.
Domicile: Where the Tax File and the Visa File Collide
The three routes for a sponsor living in Britain
Every sponsor who signs an affidavit of support must be domiciled in the United States. The instructions define domicile as the country where you keep your principal residence and plan to live for the foreseeable future. An American who has lived in London for nine years does not meet that test on the facts. Nevertheless, three routes remain open.
The first route covers certain employment abroad, including work for the US government and for an American firm engaged in developing foreign trade, or its subsidiary. The second route applies where your stay abroad is temporary and you kept your US domicile throughout. The third route is the one most London families use. You show that you intend in good faith to re-establish US domicile no later than the date your spouse is admitted.
When Form 2555 contradicts the embassy file
The second route is where tax returns do damage. To claim the exclusion as a bona fide resident, you tell the IRS on Form 2555 that you live in Britain, and you describe the nature and length of your stay. Many returns say the stay is indefinite. That statement sits badly beside a sworn claim that the stay was always temporary.
The instructions also list records of paying US state or local taxes as proof of continued domicile. This evidence cuts both ways. If you tell the embassy that California or New York remained your home, the state can ask why you filed no resident returns there. High-tax states pursue former residents who keep a domicile, and they tax worldwide income. Therefore, a domicile claim made to win a visa can open years of state tax exposure.
The cleaner route for most wealthy families
In contrast, the third route avoids both traps. You accept that you were domiciled in Britain, and you prove that you are moving back. The evidence is practical: a signed US employment contract, a lease or purchase in the United States, school places, a sale or letting of the London home, and a moving date. A joint sponsor cannot fill a domicile gap, so this evidence has to be your own.
Moreover, timing is flexible. You need not move months ahead of your spouse, because domicile only has to be established by the date of admission. Many couples travel together. Accordingly, the tax return and the domicile letter should tell the same story, which is one more reason to prefer the credit over the exclusion in the final UK years.
Using Assets for the Affidavit of Support When Income Falls Short
The three-times rule for a spouse
Assets can supplement income in an affidavit of support, or replace it. For a US citizen sponsoring a spouse, the net value must equal at least three times the shortfall between household income and the 125% figure. Other sponsors need five times. Therefore, a citizen with no qualifying income and a household of two needs $81,150 of assets, and a household of four needs $123,750.
The assets can belong to you, to a household member who signs Form I-864A, or to your spouse. The intending immigrant's own assets count without any extra form. Consequently, a British spouse's savings can carry the affidavit of support on their own. Only assets that convert to cash within one year, without considerable hardship or loss, qualify.
Which UK assets qualify
Cash, listed shares and funds in a general investment account qualify easily. A stocks and shares ISA qualifies too, since you can withdraw at any time. Net equity in a home also counts, measured as appraised value less the mortgage. However, a UK pension is different. Most personal pensions cannot be accessed before the normal minimum pension age, which is 55 now and rises to 57 in April 2028. A sponsor aged 44 cannot convert a SIPP to cash within a year, so it should not be listed.
Furthermore, assets held in Britain are acceptable in principle. Nevertheless, the officer must be convinced that the value could reasonably be made available to support your spouse in America. Clear statements, a sterling to dollar conversion and proof of ownership all help. In our experience, a single brokerage or ISA statement works better than a long list of small holdings.
The tax cost of proving and moving assets
Listing an asset on an affidavit of support costs nothing. Selling it to fund the move is where tax arrives. A sale of UK shares outside an ISA triggers UK capital gains tax at 18% or 24% and a US gain measured in dollars. Inside an ISA, Britain charges nothing, but the United States taxes the gain in full. Furthermore, most UK funds are passive foreign investment companies, which need Form 8621 and can attract punitive rates.
Similarly, the London home has its own traps. HMRC usually exempts a main residence, and the rules for tax when you sell property explain the exceptions. The IRS, however, excludes only $250,000 of gain for one owner, or $500,000 on a qualifying joint return, as IRS Topic 701 sets out. A long-held house in Kensington or Hampstead often carries a larger dollar gain than that. Additionally, repaying a sterling mortgage after the pound has moved can create a separate taxable currency gain.
Illustrative Case Study: A Private Equity Director Returns to New York
The position at the start
Daniel is a US citizen and a director at a private equity firm in Mayfair. He has lived in London for nine years and earns £420,000. His wife Charlotte is British, and they have two children who hold US passports. Daniel accepts a role in New York at $650,000 a year. Charlotte needs an immigrant visa, so Daniel must sign an affidavit of support for a household of four. The floor is $41,250.
The income is ample. However, the file is not. Daniel last filed a US return for 2021. He assumed that paying 45% tax in Britain ended his US duties. He therefore has three missed US tax returns, for 2022, 2023 and 2024, and no FBARs for accounts worth about £1.3 million. On those facts his affidavit of support is insufficient under the regulation, whatever his salary.
What the tax work changed
We prepared the three late returns and six years of FBARs under the streamlined foreign offshore route, where no penalty applies. We used the foreign tax credit and not the exclusion. As a result, each return shows total income of roughly $553,000 on line 9, and UK tax at 45% reduces the US liability to nil. An exclusion claim would have shown $423,000 and added a Form 2555 statement about an indefinite UK stay.
We filed five months before the embassy interview, so the transcripts were available. Daniel then relied on the third domicile route. His evidence was the signed New York contract, a lease in Westchester, school enrolments and the letting agreement for the London house. As a fallback, the couple listed Charlotte's ISA, worth £310,000 or about $410,000. That figure is more than three times the full $41,250 floor on its own. Daniel's SIPP of £600,000 stayed off the form, because he is 44.
The result and the lesson
The embassy accepted the affidavit of support at the first interview. The tax cost of the catch-up was nil, because foreign tax credits covered every year. In contrast, a sponsor who waits for the embassy's document request faces a late scramble, photocopies in place of transcripts and a postponed move. The lesson is simple. An affidavit of support is only as strong as the tax returns behind it, so the returns come first.
What the Move Costs in Tax on Both Sides
Your British spouse becomes a US taxpayer
A green card makes your spouse a US tax resident from the day of admission. From that date, the IRS taxes their worldwide income, including UK rents, dividends and gains. Their ISAs lose all shelter, their UK funds become passive foreign investment companies, and their accounts enter FBAR and Form 8938 reporting. Until then, the IRS rules for a nonresident spouse apply.
Therefore, the weeks before admission are valuable. A spouse who sells ISA funds before arriving pays no UK tax and no US tax, and starts American life with a higher cost base. Similarly, large gains can be realised while the spouse is still outside the US net. Our guide to pre-immigration tax planning for Britons moving to the US covers the sequence, and our cross-border planning service prepares the figures.
Leaving the UK tax net cleanly
Meanwhile, Britain does not release you on the day you fly. The statutory residence test decides your status for the whole tax year, and split-year treatment applies only if you meet a specific case, such as starting full-time work overseas. Moreover, HMRC can tax certain gains and distributions if you return within five years. The UK residence rules set out the basics.
As a result, you face a year with two tax systems. Your final UK return covers the period to departure, and your US return covers the full year. Meanwhile, New York or California will tax you as a resident from arrival. Accurate US UK tax returns preparation for that year prevents double taxation, and our treaty and foreign tax credit work matches UK tax paid to the right US income.
The contract you signed keeps running
However, the affidavit of support obligation does not end when the visa is issued. It ends only when your spouse becomes a US citizen, is credited with 40 qualifying quarters of work, leaves the United States permanently after giving up residence, or dies. Your own death ends it as well. Divorce is not on that list. Consequently, a former spouse can sue to enforce support at 125% of the poverty guidelines years after a separation.
Accordingly, two practical points follow. First, quarters you work during the marriage can be credited to your spouse, which shortens the period. Second, you must report a change of address on Form I-865 within 30 days for as long as the obligation lasts. For a wealthy sponsor the sums are small, but the duty is real and a court can enforce it.
How TaxYork Can Help
TaxYork provides comprehensive tax preparation and compliance for Americans in Britain and Britons in America. For an affidavit of support case, we prepare every missed US tax return, the related FBARs and the Form 8938 filings, and we deliver transcripts that match the figures on your form. Furthermore, we model the exclusion against the credit before you file, so the total income line supports your affidavit of support.
Moreover, we prepare the returns for the year of the move on both sides. That work covers your final UK Self Assessment, split-year claims, the US resident return, and the first US filings for your spouse. Additionally, our FBAR and FATCA reporting service brings missed reporting on pensions, investment accounts and ISAs up to date. Our clients are investors, investment bankers and company owners, and we build each file to withstand an officer's questions.
Conclusion
The affidavit of support looks like an immigration form, yet it is a test of your US tax record. The officer reads the total income line on your federal return, asks whether that income continues, and checks your domicile. Missed US tax returns make the sponsorship insufficient under the regulation. The exclusion can shrink your income on paper, and Form 2555 can contradict your domicile claim. Assets can fill a gap, but only liquid ones, and selling them has a tax cost in two countries.
Therefore, the order of work matters. File the late returns first, choose the method that shows your real income, and gather domicile evidence that agrees with your returns. Then plan your spouse's arrival date around their UK investments. Ultimately, a sponsor who settles the tax file before the petition moves faster and pays less.
Contact Us
If you plan to sponsor a British spouse and your US filings are behind or untested, speak to us before you sign an affidavit of support. You can book a consultation with our US-UK team, email hello@taxyork.com, or call 020 3488 8606. We will review your last three years of returns, confirm what the embassy will see, and prepare whatever is missing.
Written by the TaxYork Expert Team — US-UK tax specialists.
Disclaimer
This article provides general information only and reflects US and UK rules as understood in October 2026. It is not legal, immigration or tax advice for your circumstances. Immigration decisions rest with the US Department of State and USCIS, and tax outcomes depend on your full facts. Always obtain professional guidance from a qualified specialist before you file a return or sign an affidavit of support.