401(k) Rollover for UK Residents: IRA, Tax & Rules (2026)

Managing US retirement accounts from the United Kingdom is not difficult because the rules are obscure. It is difficult because two rule books apply at once, and most guidance is written as though only one of them exists. A 401(k) explainer from a US provider will not mention your UK tax residence; a UK pension article will not understand your IRA. This guide sits in the gap, and is designed to be the reference the rest of this series supports.

It is written for UK-resident US persons - and recent arrivals to the UK - who hold a 401(k), a traditional IRA, a Roth IRA, or some combination, and want to understand how to hold, consolidate, and eventually draw on them from across the Atlantic.

The account types, briefly

401(k) and traditional IRA

Pre-tax accounts: you received a deduction on the way in, growth is tax-deferred, and withdrawals are taxed as income. A 401(k) is tied to a US employer's plan; a traditional IRA is held with a US custodian and controlled by you.

Roth IRA and Roth 401(k)

After-tax accounts: no deduction going in, but qualified distributions are tax-free in the US. The UK treatment of Roth distributions is generally favourable under the treaty but not automatic - covered in detail in the dedicated Roth article in this series.

Other US accounts

SEP and solo 401(k)s for the self-employed follow broadly the pre-tax pattern. Taxable US brokerage accounts are not retirement accounts and follow different rules; they are addressed elsewhere in the wider series.

Your accounts stay in the US

There is no route to move a 401(k) or IRA into a UK SIPP or workplace pension, and no reason to try. The accounts remain US-sited and continue under US tax-deferral. When people speak of a 'rollover' in this context, they mean movement within the US system -most commonly consolidating a former-employer 401(k) into an IRA - not a transatlantic transfer. Keeping that distinction clear prevents a great deal of confusion.

The three forces that shape every decision

1. How the treaty taxes your distributions

Under the US–UK Income Tax Treaty, periodic pension distributions are generally taxable in your country of residence - the UK, for a UK resident. The saving clause preserves the US right to tax its own citizens and green-card holders, so both countries may assert taxing rights, with foreign tax credits and re-sourcing rules built to prevent the same income being taxed twice. Lump sums follow their own provisions. The net effect depends on the type of distribution and the order in which the systems apply, which is why distribution planning is a coordination exercise, not a single calculation.

2. Whether your custodian will serve a UK address

Some US custodians restrict or close accounts for non-US-resident holders, and others limit which investments a UK-resident can access. This is often the binding practical constraint - more so than tax - because an account you cannot manage is a problem regardless of its tax treatment. Confirming custodian policy is a first step, not an afterthought.

3. How dollars meet pounds

Your accounts hold dollars; your retirement is spent in pounds. The exchange rate at each conversion, the timing and frequency of conversions, and how currency risk is managed across a multi-decade retirement are central variables, not details. Currency is one of the defining features of cross-border retirement income.

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Rollover and consolidation mechanics

Where consolidation within the US system is appropriate, how it is done matters. A direct, trustee-to-trustee transfer moves funds straight between providers, is generally not a taxable event, and avoids withholding. An indirect, 60-day rollover pays the money to you, triggers mandatory US withholding, and becomes taxable - with the 10% penalty if you are under 59½ - if not completed in time. From the UK, the direct route removes most of the cross-border risk. The detailed trade-offs of consolidating, and of leaving funds in a 401(k), are covered in the dedicated rollover article in this series.

Access, penalties, and timing

The 10% additional tax on distributions before age 59½ is a US feature of the account and applies regardless of UK residence; certain exceptions exist, including the 'rule of 55' for workplace plans in some circumstances. Required Minimum Distributions from pre-tax accounts generally begin at age 73 under current US rules, rising to 75 for those born in 1960 or later; Roth IRAs have no lifetime RMDs. For new arrivals, the UK's four-year Foreign Income and Gains regime can shape how US distributions are taxed in the UK during the early years of residence. Each of these interacts with the others, which is why sequencing - the order and timing of withdrawals across accounts - is where much of the planning value sits.

Reporting, briefly

US retirement accounts held with US custodians do not usually create the foreign-account reporting that a US person's UK accounts do. The reporting that applies is a UK return reflecting distributions once you are UK-resident, and, for US citizens and green-cardholders, a continuing US return on worldwide income. The goal is a single, coordinated position across both - not two unconnected filings.

A decision checklist

1. Inventory every US retirementaccount, noting type (pre-tax or Roth), provider, balance, and currentinvestment menu.
2. Confirm, for each account,whether the provider will hold and service it for a UK-resident, and what youcould invest in.
3. Map how each account'sdistributions would be taxed under the treaty given your citizenship andresidence.
4. Decide whether anyconsolidation is worthwhile — and if so, use direct transfers — weighing whateach 401(k) feature would be given up.
5. Plan access and timing aroundthe 10% penalty, RMD ages, and, for new arrivals, the four-year FIG window.
6. Set a currency approach forconverting dollar income into pound spending over time.

An illustrative example

Consider a hypothetical dual US/UK household, both aged 55, who moved to London three years ago. Between them they hold two old 401(k)s, a traditional IRA, and a Roth IRA. Working through the checklist, they find that one 401(k) custodian will not serve their UK address while the IRA custodian will; that direct consolidation of the orphaned 401(k)into the IRA is the clean route; that their Roth is best left untouched and documented; and that their early UK years are shaped by the FIG regime. None of this is a recommendation - it simply shows how the same framework produces a tailored picture. This example is hypothetical and for illustration only.