The UK 25% Pension Lump Sum and US Tax: Why the Treaty Does Not Save It

The UK 25% pension lump sum is tax-free in Britain but generally taxable by the United States for a US citizen. The treaty gives the UK exclusive taxing rights over lump sums, and the saving clause then takes that protection away from US citizens, because the lump sum paragraph is not on the excepted list. US tax on UK pensions turns on this point.

It is the single most expensive misunderstanding in UK–US retirement planning. People take a six-figure lump sum expecting it to be tax-free, having read the UK rules, and discover a US bill on the whole amount the following April.

What the UK 25% pension lump sum is

A pension commencement lump sum lets you take up to 25% of a pension pot free of UK income tax when you start drawing benefits. Since 6 April 2024 it is capped by the lump sum allowance of £268,275, as GOV.UK sets out in its guidance on the lump sum allowance. Anything above the allowance is taxed as income in the UK.

The rest of the pot stays invested and is taxed as income in the UK when drawn. None of that is controversial. The question is what the United States does with the tax-free part.

Why the treaty does not protect it

Article 17(2) of the US–UK treaty says a lump-sum payment from a pension scheme established in one country, beneficially owned by a resident of the other, is taxable only in the country where the scheme is established. Read alone, a UK lump sum would be taxable only in the UK.

It is not read alone. HMRC's own International Manual states that paragraph 2 of Article 17 "is in effect overridden by paragraph 4 of Article 1" — the saving clause — so the country of residence may tax the payment as well, unless the provision is listed in the exceptions in Article 1(5).

The exceptions cover Article 17(1)(b), 17(3) and 17(5). Paragraph 2 is not among them. For a US citizen, whom the United States taxes on citizenship regardless of residence, that leaves the lump sum exposed to US tax.

Who is affected, and how

The first row is the painful one. The UK charges nothing, so there is no foreign tax credit to offset the US tax — the same trap that catches a UK home sale, described in selling a UK home as a US citizen.

What is actually taxed in the US

The US taxes the distribution, not the pot. The taxable amount is the lump sum less any US basis you have in the pension — typically employee contributions already taxed by the US, since UK tax relief on them does not create US basis unless the treaty was used.

Most UK pensions built from employer contributions and relieved employee contributions carry little basis, so most of the lump sum is taxable as ordinary income. It stacks on top of your other income for the year, which can push a single payment into the top bracket and into the net investment income tax range for other income.

Planning before you take it

• Take the lump sum in a year of otherwise low income, so it is taxed in lower brackets.
• Consider drawing income instead: UK tax on pension income is creditable against the US tax on it, while the tax-free lump sum creates a US charge with nothing to credit.
• Spread crystallisation across tax years where the scheme allows.
• Time it against a move: a US citizen already back in the United States pays UK tax on the lump sum and can credit it.
• Check your US basis in the pension before assuming the whole amount is taxable.
• Keep contribution records: the deduction position is in UK pension contributions and US tax.

The reporting is separate again — the pension itself sits on Form 8938, covered in reporting a UK SIPP, and the treaty framework in the UK–US tax treaty.

Tranzesta models the lump sum against drawdown across both systems before you instruct the provider, because the decision cannot be reversed once the money is paid. Book a consultation before you crystallise.

Frequently Asked Questions

Is the UK 25% tax-free lump sum taxable in the US?

For a US citizen, generally yes. Article 17(2) of the US–UK treaty gives the UK exclusive taxing rights over lump sums, but the saving clause in Article 1(4) overrides it because paragraph 2 is not among the exceptions listed in Article 1(5). The lump sum is therefore normally taxable as ordinary income on the US return.

Can I claim a foreign tax credit on my UK pension lump sum?

Not if the UK charged no tax. The foreign tax credit relieves foreign tax actually paid, so a lump sum that is tax-free in the UK produces no credit, leaving the US tax payable in full. Only amounts above the lump sum allowance, which the UK does tax, generate creditable tax.

What is the UK lump sum allowance?

£268,275 since 6 April 2024, unless you hold a protected allowance. It caps the total tax-free lump sums you can take across all your pensions, replacing the old lifetime allowance. Lump sums above it are taxed as income in the UK at your marginal rate.

Would taking pension income instead be better?

Often, for a US citizen living in the UK. Regular pension income is taxed by the UK, and that UK tax is generally creditable against the US tax on the same income, so the combined bill is usually the UK bill. The tax-free lump sum reverses that by creating US tax with no foreign tax to credit against it.

Does it matter whether I live in the UK or the US when I take it?

Yes. A US citizen living in the United States who takes a UK lump sum is generally taxed on it by the UK under Article 17(2), and that UK tax can then be credited against the US tax. A US citizen living in the UK receives it free of UK tax and faces US tax with no credit available.

How does this work for an American in the UAE?

The UAE levies no personal income tax and has no income tax treaty with the United States, so a UK lump sum paid to a US citizen living in Dubai is taxed by the UK under its domestic rules and by the United States on citizenship. Any UK tax paid can be credited on the US return, but the UAE offers no relief of its own.