The six figure balance on your return that may be worth nothing

Figures relate to tax year 2025-26 (UK) · 2025 (US)

There is a date attached to every credit on your American return, and after it passes the credit is gone. Ten years, counted from the year you earned it.

Nobody writes to tell you. The balance simply shrinks at the bottom while a new layer piles on at the top.

That matters because a tax credit carryover is not savings. It is an option that expires, and for most people in Britain the chance to exercise it comes once, if at all.

Key takeaways

• Excess credits go back one year, then forward ten.
• The carryback is compulsory before anything carries forward.
• Credits stay locked inside the basket that produced them.
• British salary credits cannot offset American investment income.
• The balance expires silently after the tenth year.
• Using the earned income exclusion shrinks the credit you generate.
• The balance is still worth tracking, because the right year uses it.

Which years actually use the balance?

Years when American tax on foreign income exceeds the British tax on it, which is rarer than people hope. A sabbatical, a year of low British earnings or a move to a lower taxed country can all do it. So can a year with a large British gain taxed at a modest rate.

In our practice the most common trigger is leaving Britain partway through a year.

The second most common is a year of unpaid leave.

What about a year you leave Britain?

That is often the best year the balance will ever see. British tax falls away partway through while American tax continues on the full year. Foreign income remains in the picture for the British months, so the credit limit can absorb a real amount of the carryforward.

Plan the timing of a move with that in mind where you can.

A departure in January behaves very differently from one in November.

What if you return to the United States?

The balance travels with you, though it becomes harder to use once your income is wholly American. Any remaining foreign income keeps the door open, so British rental property or a British pension still helps. Without foreign income the carryforward simply runs out the clock.

A final British gain in the year of the move can be worth timing carefully.

Our guide to moving back to the US covers the wider checklist.

Does a British bonus help?

Only if the American tax on it exceeds the British tax, which a bonus rarely achieves on its own. Bonuses usually arrive at the highest British rate, generating still more excess credit. They grow the balance rather than spending it.

The exception is a bonus paid after you leave Britain and taxed lightly there.

Those payments can mop up a surprising amount of old carryforward.

A worked example

Take an illustrative example. An American consultant in London earns £140,000 and pays British tax at the higher and additional rates.

Her British tax comfortably exceeds the American tax on the same income. Each year she generates roughly $20,000 of excess credit in the employment basket.

After eight years the balance reads over $160,000. None of it has ever reduced a dollar of American tax.

Then she sells a British rental property. That gain is foreign income in a different basket, so the balance still cannot touch it.

The two directions compared

What is a tax credit carryover?

The part of your foreign tax that American rules would not let you use this year. You paid it, you claimed it, and the limit stopped it short. Rather than losing it outright, the system parks the excess tax credit carryover and lets you try again in other years.

The limit itself is simple enough in principle. America never credits more than the American tax on that foreign income.

Pay 45 per cent in Britain against an American rate of 37 per cent and the difference has nowhere to go this year.

How long does the balance last?

One year backwards and ten years forwards, which sounds generous until you look at the detail. The carryback is not optional, so the excess tests the previous year first. Only the tax credit carryover that survives that test moves forward, and anything still unused after the tenth year disappears.

According to IRS guidance on the foreign tax credit, the ten year period runs from the year the credit arose.

Nobody sends a warning when a tranche expires.

Why are the credits trapped by basket?

Because American law sorts foreign income into categories and applies the limit to each one separately. Salary falls in the general category while interest and dividends fall in the passive one. Credits generated in one category can never offset American tax arising in another.

So a large employment tax credit carryover sits helpless beside a bill on investment income.

Our guide to the Form 1116 income baskets sets out how the sorting works.

Does a Roth conversion use the balance?

Rarely, because a conversion creates American source income and the credit only offsets American tax on foreign income. The balance sits on the wrong side of the line. People reach for this idea often, and it almost never works as hoped.

A treaty resourcing position occasionally changes that for pension income specifically.

Even then the analysis is narrow and needs documenting on the return.

What about self employment income?

British trading profits fall in the general category alongside salary, so they add to the same pool. Social security contributions are different, since a totalisation agreement decides which country collects them. Those contributions never generate a creditable foreign tax.

Our guide to the certificate of coverage explains that split.

So a sole trader builds the balance faster without widening what it can offset.

Does the exclusion reduce your carryover?

It does, and the effect runs deeper than most people expect. Income you exclude stops being creditable income, so the British tax attached to it drops out of the calculation. You therefore generate less credit while also needing less.

For 2025 the exclusion caps at $130,000, so high earners still generate plenty of credit above it.

Our guide to the foreign earned income exclusion covers the interaction.

Can you choose not to carry back?

Not for the general rule, because the previous year absorbs whatever it can before anything moves forward. What you can control is whether to claim the credit at all in a given year, or to deduct the foreign tax instead. That choice reshapes the balance considerably.

Deducting rather than crediting wastes value in most cases.

It occasionally helps somebody whose balance is already hopeless.

Does the accrual election matter?

A great deal, because it decides which American year receives British tax paid for a British year. Electing the accrual method matches the tax to the year it relates to rather than the year you paid it. That election is binding once made, for every later year.

Most expatriates in Britain benefit from it, since the tax years overlap awkwardly.

Changing your mind afterwards is not a realistic option.

What happens when British tax is adjusted later?

You revisit the American year it belongs to, which can revive or reduce a tax credit carryover several years back. An HMRC enquiry settled in 2025 covering 2021 reaches into American returns for the same period. The redetermination rules require you to tell the IRS.

Our guide to HMRC enquiries for US filers explains the sequence.

Refunds of British tax cut the credit and can create an American liability.

Can treaty resourcing unlock the balance?

Sometimes, because the treaty lets certain American source income count as foreign for credit purposes. That re-sourced income sits in its own basket for each article relied on. It is a narrow door rather than a general solution to a trapped balance.

Pension income is the usual candidate, and the analysis needs care.

Our treaty relief service covers positions of that kind.

Does it pass to your spouse?

Only where you filed jointly in the year the credit arose, since the balance belongs to the return rather than the person. Switching from joint to separate filing can strand part of it. Divorce raises the same question in a sharper form.

Allocate the balance deliberately rather than letting software guess.

In our practice this is the detail separation agreements forget most often.

How do you track the balance properly?

A reconciliation schedule accompanies the credit form and records each year's addition, use and expiry. It has to be kept in order, because the oldest credits are used first. Skip a year and the ordering breaks permanently.

Keep your own spreadsheet alongside it rather than relying on software memory.

Changing preparers is where most balances get lost.

What if a previous preparer never tracked it?

Then rebuild it from the returns themselves, year by year, before the oldest tranches expire. The figures exist on each year's credit form even where nobody carried them forward. Reconstruction takes time and usually recovers more than it costs.

Start with the oldest year still inside the ten year window.

In our practice we rebuild several of these every filing season.

Does state tax interact with it?

Not at all, which catches people from states that still claim them. A tax credit carryover is a federal concept, and most states give no credit for foreign tax in the first place. Breaking state residence properly is therefore a separate exercise.

Our guide to state tax for expats covers the usual problem states.

The federal balance never helps a state bill.

What records should you keep?

Keep every year of tax credit carryover working, the reconciliation schedule and the British tax computations behind them. Together they prove both the amount and the year, which is exactly what an examiner asks for.

Keep them for longer than the usual period, because a ten year carryforward outlives the ordinary record retention window.

Eleven years is the safe answer.

How to manage the carryover

1. Rebuild the balance from the oldest open year forwards.
2. Separate it by basket, since the baskets never mix.
3. Note the expiry year attached to each tranche.
4. Check whether a carryback to last year is available.
5. Model the exclusion against the credit before each filing.
6. Decide on the accrual election while you still can.
7. Flag any year with low British tax as a chance to use it.
8. Carry the schedule across whenever you change preparer.

Mistakes and penalties we see with a tax credit carryover

The first is treating the balance as money in the bank. Most of it never becomes anything.

The second is mixing baskets, which overstates the tax credit carryover and invites an adjustment.

The third is losing the schedule on a change of adviser, which effectively deletes the balance.

The fourth is ignoring a British adjustment, since the redetermination rules carry penalties of their own.

How US UK Tax Accountants helps

We rebuild carryover schedules from old returns and tell you honestly which parts can ever be used. Then we look for the years that could absorb them before they expire.

Where a client plans to leave Britain, we model the departure year specifically, because that year usually offers the only real chance to spend an old balance.

If your return shows a balance nobody has ever explained, get in touch and we will work out what it is worth.

Last reviewed 12 October 2026. This article is general information and not personal tax advice. Credit positions turn on detail, so take advice on your own figures.