The UK Personal Savings Allowance and Your US Return

The UK personal savings allowance is a nil-rate band, not an exemption: interest inside it is still taxable income, just taxed at zero. So it generates no UK tax, no foreign tax credit, and the interest is fully exposed to US tax on your Form 1040.

That is the whole problem in one paragraph, and it is a problem precisely because the UK relief works so smoothly. Your bank pays interest gross, HMRC collects nothing, nothing appears on a Self Assessment return if you are not in the system, and the money feels tax-free. For a US citizen it is not tax-free — it is tax-free in one country and fully taxable in the other, with no relief flowing between them.

Key takeaways

The personal savings allowance is a nil rate of tax applied to a band of savings income, not a slice of income removed from charge. The interest remains taxable income in the UK.
Because the UK rate applied is zero, no UK tax is paid, so there is nothing to credit on Form 1116. The US tax on that interest stands in full.
The allowance shrinks as you move up the rate bands and disappears at the additional rate, so the exposure is largest for exactly the people who notice it least.
ISA interest and Premium Bond prizes are worse, not better: UK-exempt, US-taxable, and still with no creditable UK tax behind them.
UK interest has to be rebuilt on a calendar-year basis and converted to dollars for the US return; the Self Assessment figure cannot simply be copied across.
The accounts producing the interest usually trigger FBAR and Form 8938 reporting in their own right, regardless of how small the interest is.

What is the personal savings allowance, exactly?

GOV.UK's guidance on tax on savings interest describes an amount of savings income you can receive each year without paying tax on it, with the size of that amount depending on which income tax band you fall into: a larger allowance for basic-rate taxpayers, a smaller one for higher-rate taxpayers, and none at all once you are taxed at the additional rate. There is also a separate starting-rate band for savings, available only to people whose non-savings income is low enough.

The mechanics matter more than the amounts. Parliament did not carve savings income out of the charge to income tax. It created a nil rate that applies to the first slice of savings income within the relevant band. The interest is included in your total income, it counts towards the thresholds that decide which band you are in, and it affects the taper of other reliefs. It is simply charged at a rate of zero.

In purely domestic terms, the distinction is academic — nil tax is nil tax. Across the Atlantic it decides everything.

Why does a nil-rate band leave you with no foreign tax credit?

The US foreign tax credit is a credit for foreign tax paid or accrued. It is not a credit for income that a foreign country chose to tax lightly, or for income the foreign country could have taxed and did not. If the UK applies a rate of zero to a band of your interest, your UK tax liability on that interest is zero, and zero is the number that flows to Form 1116.

So the usual expat arithmetic breaks down. For salary, UK income tax is typically high enough that the credit wipes out the US tax on the same income and leaves a carryover. For savings interest covered by the allowance, there is no UK tax at all, and the US tax lands undiluted at your ordinary marginal rate. The fact that you are sitting on a comfortable pile of excess credits from your employment income does not help: Form 1116 is computed basket by basket, and interest is passive-category income, while employment income sits in the general category. Excess general-basket credits cannot be redirected to cover passive-basket tax. Our note on foreign tax credit carryovers and baskets sets out why the walls between baskets are so rigid.

This is the same structural point we make about which UK taxes are creditable at all: the credit follows the tax actually imposed, not the economic burden you feel.

How does UK interest get onto a US return?

UK bank and building society interest is ordinary income for US purposes, reported on Schedule B of Form 1040 alongside domestic interest — see the IRS summary at Topic no. 403, Interest received and the Schedule B instructions. It does not get the preferential rates that apply to qualified dividends or long-term gains. It is taxed as plain income.

Three mechanical points cause most of the errors we correct:

Different years. The UK tax year ends on 5 April; the US return is for the calendar year. You cannot lift the interest figure from your Self Assessment return. It has to be rebuilt from the bank's own statements on a January-to-December basis.
Currency. Interest is translated into US dollars. Where interest is credited through the year, translating each credit at the rate for that date is the defensible method; a single year-end rate is a shortcut that can distort a volatile year.
Joint accounts. A UK joint account held with a non-US spouse is not automatically split in the way the bank's paperwork implies. Who is taxed on what depends on beneficial ownership, and it needs deciding deliberately rather than by default.

Schedule B also asks directly whether you have an interest in, or signature authority over, a foreign financial account — which is where the reporting layer begins.

ISAs and Premium Bonds: the version of this that hurts more

If the personal savings allowance is an inconvenience, ISAs are the sharper version of the same trap. ISA interest and growth are exempt from UK tax entirely. The US does not recognise the ISA wrapper, so the income inside it is taxed in the US as it arises — and because the UK charged nothing, there is no creditable UK tax behind it at all.

A stocks-and-shares ISA can be worse still, because UK-domiciled funds and investment trusts held inside it are typically passive foreign investment companies for US purposes, which brings a punitive regime and extra forms with it. Premium Bond prizes follow the same shape: exempt in the UK, ordinary income in the US, no credit.

The common thread is that the more effective a UK savings relief is, the worse the US outcome, because the relief removes the only thing that could have sheltered you on the other side.

Does the treaty fix it?

Not in the way people hope. The US–UK double taxation convention allocates interest primarily to the state of residence, but the saving clause preserves the United States' right to tax its own citizens as if the treaty had not come into force, with only limited exceptions. A US citizen resident in the UK is therefore taxable in both places as a starting point, and the treaty's answer to double taxation is relief by credit — which brings us back to the problem that there is no UK tax to credit.

Where the treaty does real work here is on source. Its relief article contains re-sourcing rules that can treat income as having a foreign source for the purpose of computing the US credit, which matters when the UK has taxed income the US would otherwise regard as US-source. That is a genuine planning tool, but it is a tool for using credits you have, not for manufacturing credits you do not.

If you are not UK resident

The analysis flips. A US citizen who is not UK resident and holds a UK savings account is usually in the disregarded income rules rather than the personal savings allowance. Under those rules UK tax on savings and investment income can be limited to the tax, if any, deducted at source — but taking that limit means personal allowances are not given against your other UK income. It is a choice between two computations, not a combination of both.

The US consequence is the same either way, and for the same reason: whichever route produces less UK tax produces less creditable tax. We work through the entitlement side of that trade-off in our piece on claiming the UK personal allowance as a US citizen who is not UK resident.

The reporting layer nobody budgets for

The tax on a few hundred pounds of interest is rarely the real cost. The reporting is.

A UK savings account is a foreign financial account. Once your foreign accounts in aggregate pass the reporting threshold at any point in the year, an FBAR is due — and the threshold is tested across all your accounts together, not account by account, so a small savings pot can be the item that tips a current account and a pension over the line. Form 8938 is a separate test with its own thresholds and its own penalties, and the two overlap without replacing each other. If you have been filing US returns without either, that is a fixable problem, but it is fixed through a disclosure route rather than by quietly starting this year.

What actually helps

There is no clean way to make UK-exempt interest US-exempt. What is available is better sequencing:

Decide which spouse holds the cash. In a mixed-nationality marriage, interest earned by the non-US spouse on their own account, from their own funds, is outside the US net entirely. That is an ownership decision, not a paperwork one, and it has UK and estate consequences that need thinking through first.
Weigh the UK relief against the US cost before using it. A UK saver's reflex is to fill the ISA first. For a US citizen the ISA is usually the worst available wrapper, and ordinary taxable holdings in US-domiciled funds often produce a better combined result.
Watch what the interest does to your bands. Savings income counts towards the thresholds that shrink the personal allowance and the savings allowance itself, so a lump of interest can cost more than the tax on the interest.
Keep the credit position clean. If you are also running a rental or self-employment, the passive basket is where this interest lives, and it is worth knowing whether that basket has capacity before year end.

Our calculators let you sketch the UK side, the US-UK private client tax service covers the wrapper-and-ownership questions above for households with real savings and investment positions, and the US-UK tax specialists desk runs both returns as a single engagement. If you want a scoped fee before committing, request a quote.

Every return and credit computation we prepare is reviewed and signed by an IRS Enrolled Agent who is also ACCA-qualified, so the UK treatment and the US consequence are judged together rather than in sequence by two advisers.

Reviewed by an IRS Enrolled Agent who is also ACCA-qualified. This article explains general principles and is not advice on your own facts. Allowance amounts and bands change; confirm the current figures and your own position before acting.

Frequently asked questions

Is UK savings interest covered by the personal savings allowance taxable in the US?+

Yes, in full. The allowance applies a nil rate to a band of savings income; it does not remove that income from charge. The interest is ordinary income for US purposes, reported on Schedule B of Form 1040 and taxed at your marginal rate. Because the UK rate applied was zero, there is no UK tax paid and therefore nothing to claim as a foreign tax credit against it.

Can I use my excess foreign tax credits from UK employment income to cover the tax on this interest?+

No. The foreign tax credit is computed basket by basket on Form 1116. Interest is passive-category income, while employment income sits in the general category, and credits cannot be moved between baskets. A large general-basket carryover from a UK salary does nothing for US tax on passive-basket interest.

Are ISAs treated better or worse than ordinary UK savings for a US citizen?+

Worse. ISA interest and growth are exempt from UK tax, so there is no creditable UK tax at all, while the US taxes the income inside the wrapper as it arises because it does not recognise the ISA. A stocks-and-shares ISA is usually worse again, because UK funds and investment trusts held in it are typically passive foreign investment companies for US purposes, with a punitive regime and extra reporting. Premium Bond prizes follow the same pattern: UK-exempt, US-taxable, no credit.

Can I just copy the interest figure from my Self Assessment return onto my US return?+

No. The UK tax year ends on 5 April and the US return covers the calendar year, so the interest has to be rebuilt from bank statements on a January-to-December basis and translated into US dollars. Where interest is credited through the year, translating each credit at the rate for its date is the defensible approach. Joint accounts held with a non-US spouse also need the beneficial ownership settled rather than assumed.

Does the US-UK treaty stop this double taxation?+

Not here. The treaty allocates interest primarily to the state of residence, but the saving clause preserves the United States' right to tax its own citizens as though the treaty did not apply, subject to limited exceptions. Its answer to double taxation is relief by credit, which returns you to the original problem: the UK charged no tax, so there is no credit to take. The treaty's re-sourcing rules help you use credits you already have; they do not create credits where none exist.