Introduction: Offshore Interest and the Reform HMRC Quietly Shelved
Your offshore interest still has to be sliced into a British tax year that no bank on earth reports on. HMRC spent eighteen months consulting on a fix. However, on 15 July 2026 the government published its summary of responses and confirmed it is not proceeding.
The exact words matter. The lack of consensus and the range of issues raised meant that no formal proposals were made. Therefore, the mismatch that has irritated every internationally mobile taxpayer for decades remains untouched.
For most British taxpayers, that outcome is an administrative nuisance. For Americans living in Britain, it is considerably worse. Specifically, you now reconcile three calendars, and the money at stake runs into five figures for a wealthy household.
Why Offshore Interest Hurts Americans More Than Anyone Else
Here is the point almost every guide misses. When HMRC says offshore interest, it means interest arising outside the United Kingdom. Consequently, for an American in London, your offshore interest is usually American interest: Treasury money-market funds, deposit accounts and brokerage cash held in the United States.
That single fact creates the problem. Britain taxes that income because you live here. Meanwhile, the United States treats it as US-source income, which means your default foreign tax credit position is nil. Furthermore, the timing never lines up, so even the correct figure lands in the wrong year.
What the Government Actually Decided
The consultation ran from 30 October 2024 to 22 January 2025. HMRC received just 19 written responses, comprising six representative bodies, six professional advisers and seven individuals. Notably, every respondent agreed the mismatch was real.
Nevertheless, agreement stopped there. Over 40% argued the scope should widen to cover all offshore investment income rather than interest alone. Consequently, the government shelved the measure and said it would continue to consider the area. You can read the summary of responses on offshore interest in full.
What Offshore Interest Means, and Why the Dates Never Line Up
Britain taxes UK residents on worldwide income. Accordingly, interest from a New York bank, a Jersey deposit or a Swiss account is taxable here. It is treated exactly like interest from a Manchester building society. HMRC explains the basics in its guidance on tax on foreign income.
The Arising Basis and the British Tax Year
Interest is charged as it arises. The rule sits in Part 4 of the Income Tax (Trading and Other Income) Act 2005. The statutory framework for savings and investment income sets the rule, and HMRC's savings and investment manual works through the detail.
Consequently, your return covers 6 April to 5 April. That period exists nowhere else in the financial world. Moreover, no overseas bank produces a statement to match it.
Where the Calendar Year Comes From
Two forces push this income onto a calendar year. First, foreign banks and brokers close their books on 31 December, so your tax pack, your 1099-INT and your interest certificate all run January to December. Second, automatic exchange of information works the same way.
More than 100 jurisdictions exchange financial account data under the Common Reporting Standard, and HMRC sets out the mechanics in its automatic exchange of information guidance. Importantly, that data reaches HMRC on a calendar-year basis. Therefore, HMRC compares calendar-year data against a tax-year return and sees a discrepancy that may not exist.
The Apportionment Nobody Enjoys
You therefore split every certificate. Specifically, you take the portion arising from 6 April to 31 December in one calendar year. You then add the portion arising from 1 January to 5 April in the next. Furthermore, you must do it on an arising basis rather than a payment basis where the two differ.
For a single deposit account, that exercise takes ten minutes. However, for a wealthy household running money-market funds, multiple currencies and rolling fixed-term deposits, it takes hours and produces figures nobody can audit easily.
The Reform That Would Have Fixed It, and Why It Failed
HMRC's proposal was elegantly simple. Understanding why it collapsed tells you what to expect next.
What HMRC Proposed for Offshore Interest
The government asked whether offshore interest should be taxed on a calendar-year basis instead. Under the proposal, the interest taxable in a UK tax year would be the amount arising in the calendar year ending within it. For example, the tax year ending 5 April 2026 would have captured interest arising in the twelve months to 31 December 2025.
Consequently, your foreign tax pack would have dropped straight onto your return. Additionally, HMRC's exchange-of-information data would have matched the declared figure exactly. The original consultation document on simplifying the taxation of offshore interest sets out the reasoning.
Why the Consultation Collapsed
Three objections proved fatal. Firstly, the change would have created two different reporting periods inside one return, because UK interest would still run to 5 April. Secondly, respondents split over whether the reform should be mandatory or elective. Thirdly, and most damagingly, more than 40% wanted dividends and other offshore investment income included too.
Meanwhile, the transitional year presented its own difficulty. Moving from one basis to another risks either taxing a stub period twice or letting it escape entirely. Ultimately, the government preferred no change to a contested one.
What Happens Now
Nothing changes, and that is the practical answer. The apportionment obligation continues for 2026/27 and beyond. Therefore, plan on the current rules remaining in place indefinitely, while accepting that HMRC has explicitly reserved the right to revisit them.
Additionally, expect data-driven enquiries to continue. HMRC issues large volumes of prompted correspondence about overseas income, and calendar-year data mismatched against tax-year returns is precisely what generates them.
The American Problem: Your Offshore Interest Is Usually US Interest
This section covers ground that no British guide to offshore interest addresses at all. Consequently, it is where most of the recoverable money sits.
Sourcing, and Why the Foreign Tax Credit Fails by Default
Interest is sourced by the residence of the payer under section 861 of the Internal Revenue Code. For readers new to the concept, Investopedia explains income sourcing rules in plain terms. Accordingly, interest paid by a US bank is US-source income, even though you live in London and Britain taxes it.
The consequence is brutal. The foreign tax credit relieves US tax on foreign-source income. However, your US-source offshore interest generates no foreign-source income in the passive basket. Therefore, the UK tax you paid on it has nothing to offset, and it strands.
In our experience preparing returns for wealthy Americans in Britain, this is the single most common and most expensive error we correct. Furthermore, it repeats year after year until somebody notices.
Article 24(6) Re-sourcing and the Separate Form 1116
The treaty solves it, provided you claim properly. Article 24(6) of the US-UK income tax treaty re-sources certain income to the United Kingdom for credit purposes. The treaty texts sit on the IRS website.
Critically, re-sourced income belongs in its own basket. Consequently, you file an additional Form 1116 marked for treaty re-sourced income, separate from your general and passive baskets. Moreover, the credit is capped at the US tax on that income, so relief is real but bounded.
One further limit deserves emphasis. The net investment income tax of 3.8% sits outside the foreign tax credit entirely. Therefore, a slice of your UK tax on offshore interest stays permanently unrelieved regardless of how well you draft the claim.
Schedule B, FBAR and Form 8938
Reporting runs alongside the tax. You list every payer on Schedule B, and Part III asks directly whether you hold foreign financial accounts. That answer is a sworn statement, so treat it accordingly.
Additionally, aggregate foreign account balances above $10,000 at any point trigger the FBAR filed with FinCEN. Separately, Form 8938 applies at much higher thresholds for residents abroad, beginning at $200,000 on the last day of the year for single filers. Notably, the two forms overlap without replacing each other.
Three Calendars, One Return
An American in Britain reconciles the UK tax year, the US calendar year and the bank's calendar year. Consequently, three mechanisms deserve attention.
The Section 905(a) Accrual Election
Most individuals claim the foreign tax credit on a cash basis. However, UK tax on offshore interest is settled through payments on account in January and July. That pattern routinely drops two years of UK tax into one US calendar year. Therefore, credits bunch in one year and run dry in the next.
The election under section 905(a) lets you claim the credit on an accrual basis, matching UK tax to the year the income arose. Nevertheless, weigh it carefully. The election is irrevocable, and it binds every future year.
Currency, and the Rate You Use
You translate twice, and the two translations use different rules. For HMRC, you convert the income into sterling using an acceptable exchange rate for the UK tax year. For the IRS, you report in dollars, which for US-source interest requires no translation at all.
Consequently, the sterling figure on your UK return and the dollar figure on Schedule B will not reconcile arithmetically. That is correct rather than wrong. Furthermore, you should document the method, because an unexplained gap invites questions from both sides.
The April 2027 Rate Rise Already Legislated
Autumn Budget 2025 confirmed that savings income rates rise by two percentage points from April 2027. Accordingly, the basic rate moves to 22%, the higher rate to 42% and the additional rate to 47%. The personal savings allowance and the starting rate band remain unchanged, and current income tax rates still apply until then.
For an American, the rise is not neutral. Specifically, a higher UK charge buys no extra US relief once the treaty credit already covers the US tax. Therefore, the increase falls entirely on you.
Case Study: $96,000 of American Interest, Taxed in London
Consider a US citizen who has lived in London for nine years. She is an additional-rate taxpayer, so her personal savings allowance is nil.
The Position
She holds roughly $2 million in US Treasury money-market funds and deposit accounts, producing $96,000 of interest in calendar year 2025. Additionally, she holds a Jersey deposit paying £14,000. All of it counts as offshore interest for HMRC.
The Numbers
Apportioning to the UK tax year 2025/26 gives approximately $95,500 of US interest, which converts to about £72,500. Adding the Jersey deposit produces £86,500 of taxable savings income. At the 45% additional rate, the UK charge is £38,925.
On the American side, the calendar-year figure of $96,000 attracts federal tax at 37%, giving $35,520, plus net investment income tax of $3,648. Consequently, she faces roughly £38,925 and $39,168 on substantially the same money.
The Fix, and What It Recovers
Without a re-sourcing claim, the US interest produces no foreign-source income, so the UK tax on it strands completely. With a treaty claim on a separate Form 1116, she credits UK tax against the $35,520 of federal tax on that income. Therefore, the claim recovers roughly $35,520 that she would otherwise simply lose.
The 3.8% net investment income tax of $3,648 remains payable regardless. Furthermore, a section 905(a) accrual election smooths the January and July payment pattern so the credit lands in the year the interest arose. In our experience, correcting all three points together changes the outcome by more than $35,000 in a single year.
What To Do Before the 2026/27 Return
Preparation beats correspondence. Accordingly, three steps deserve your attention this year.
Build the Bridge Schedule Once
Create a single working paper that runs each account monthly for a full calendar year. It should then apportion the totals to the UK tax year. Consequently, one schedule serves both returns, and the same document answers any HMRC query.
Furthermore, keep it. HMRC's assessing window for offshore matters extends to twelve years, so a schedule you can reproduce in a decade is worth building properly now.
Deal With Missed Reporting Before HMRC Writes
Where earlier years understated your offshore interest, correct them voluntarily. The Worldwide Disclosure Facility provides the UK route, and an unprompted disclosure attracts materially lower penalties than a prompted one.
Additionally, address the American side in the same exercise. Where US returns or FBARs were missed for the same accounts, our IRS Streamlined Filing service brings them current. Professional commentary on cross-border compliance is also published by the ICAEW tax faculty and the AICPA tax section.
Review the Structure, Not Just the Return
Finally, ask whether holding large dollar cash balances in the United States still serves you. Specifically, the sourcing rule that strands your credit follows the payer, not the currency. Therefore, where the same cash sits, the answer changes, and our cross-border tax preparation services start from that question.
How TaxYork Can Help
TaxYork prepares both returns for wealthy Americans living in Britain. Consequently, one team owns the reconciliation, rather than two teams blaming each other for it.
Our work on offshore interest begins with the bridge schedule, built from your actual statements rather than a summary. Furthermore, we test every interest stream for sourcing, then draft the Article 24(6) re-sourcing claim and the separate Form 1116 that makes it stick. That work sits alongside our US tax return preparation for expats.
Additionally, we model the section 905(a) election before you make it, because it cannot be undone. Where treaty positions drive the outcome, our tax treaty optimisation service handles the analysis and the disclosure.
Conclusion
HMRC looked at the offshore interest mismatch, consulted properly, and decided the cure was worse than the disease. Consequently, the apportionment burden is now permanent in every practical sense.
For Americans in Britain, that decision matters far more than the muted UK coverage suggests. Specifically, your offshore interest is usually US-source, which strands your foreign tax credit unless you claim treaty re-sourcing on a separate form. Moreover, the April 2027 rate rise lands squarely on you rather than on the US Treasury.
Above all, build the schedule once and claim the treaty properly. Ultimately, the households that lose money here are not the ones with complicated affairs. They are the ones whose returns were prepared on one side of the Atlantic at a time.
Contact Us
Our specialists prepare US and UK tax filings for high-net-worth individuals, investors and company owners. Cross-border reconciliation is our core work. To review your position before the next filing season, book a consultation with our team. Alternatively, email hello@taxyork.com or telephone 020 3488 8606.
Disclaimer
This article provides general information on UK and US tax reporting requirements. It does not constitute tax advice for any particular person or business. Tax rules change frequently. Moreover, rates, thresholds and consultation outcomes described here reflect the position as at September 2026 and may alter. Accordingly, you should obtain professional guidance tailored to your circumstances before acting. TaxYork accepts no liability for action taken solely on the basis of this article.