Which Retirement Account Should You Withdraw From First? UK Pension vs IRA vs 401(k) Withdrawal Order

When retirement income can come from a UK pension, a 401(k), an IRA, and eventually two state pensions, the order in which you draw on them changes how much tax you pay, sometimes by a wide margin.

This article is aimed at UK-origin US residents approaching or in retirement, holding both a UK pension and US accounts. It explains why withdrawal order matters across two tax systems and the categories of considerations that shape an efficient sequence. It is educational and does not constitute personal advice.

Why Withdrawal Order Matters Across Two Tax Systems

Sequencing is the lever that converts a pile of accounts into a year-by-year income plan. Each pot in a transatlantic retirement is taxed differently in the US, and each interacts with the UK side in a different way. Drawing the wrong pot first can mean paying tax that could have been deferred, wasting a lower bracket year, or losing foreign tax credit that does not carry forever.

Three forces shape the calculus. First, US marginal brackets: ordinary income brackets and qualified-dividend/long-term capital gains brackets behave differently as income rises. Second, the foreign tax credit (FTC): UK tax paid on UK pension income flows into the US tax return as a credit, but only if there is US tax in the right basket to absorb it. Third, Required Minimum Distributions: from age 73 (rising to 75 for those born1960 or later under SECURE 2.0), traditional 401(k) and IRA balances begin forcing taxable withdrawals whether the income is needed or not.

The Building Blocks of a Transatlantic Retirement Income

Six categories of pot are common in this picture. Each carries its own default US tax treatment and its own sequencing characteristics.

UK Pension Flexible Drawdown

Income drawdown from a UK personal or workplace pension is taxed in the US as ordinary income under Article 17(1) of the US-UK Income Tax Treaty. UK tax, where withheld, generally flows through the foreign tax credit. The pot is GBP-denominated and converts to USD at the rate on the date of distribution.

The UK 25% Tax-free Element

Historically taken as a tax-free lump sum under UK rules. The US treatment of this element for a US-resident member is unsettled: the conservative position treats it as US ordinary income; more aggressive treaty positions are sometimes argued. Whichever position is taken, it needs to be documented in writing with a qualified cross-border tax adviser before the withdrawal is processed.

Traditional 401(k) and IRA

Pre-tax US balances are taxed as ordinary income on withdrawal. RMDs begin at age 73 (rising to 75 for those born 1960 or later). Withdrawals before age 59½ generally carry a 10% additional tax unless an exception applies.

Roth IRA

Qualified Roth distributions are not US-taxable. Roth balances are not subject to RMDs for the original owner. The pot is, in sequencing terms, the most flexible, its main role is as a bracket-management reserve and a legacy asset.

Taxable US Brokerage

Sales generate capital gains taxed at preferential rates if long-term, ordinary if short-term. Tax-loss harvesting, basis step-up at death, and qualified dividend treatment make this account the most flexible bracket-management tool in the early years.

UK State Pension and US Social Security

Both are inflation-linked income streams claimable from defined ages. Sequencing here means choosing when each is claimed, at full retirement age, earlier, or deferred to 70 (for US Social Security) or deferred under UK rules for the UK State Pension. The Social Security Fairness Act of 2023, signed 5 January 2025, removed the WEP/GPO reduction that a UK private pension previously imposed.

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The Sequencing Considerations, Neutrally Framed

Five educational considerations show up in almost every transatlantic drawdown decision. They are described here as categories of factors, not as recommendations.

Filling Lower US Brackets Earlier

Most households see their lowest US ordinary-income brackets between the end of paid work and the start of RMDs at73. Income drawn or converted during this window often crosses fewer brackets than the same income drawn later. UK pension drawdown, traditional IRA withdrawals, and Roth conversions all sit inside this lever.

Managing the Foreign Tax Credit So UK Tax Paid is Not Wasted

FTC sits in the passive-category basket for UK pension income and carries one-year carryback and ten-year carryforward under Section 904(c). If UK tax paid in a given year exceeds the US tax in the same basket, the excess can be carried forward, but only for ten years. Concentrating UK drawdowns into years with insufficient US passive-basket income can strand FTC.

Coordinating Around RMD Onset at 73

RMDs reduce optionality. From 73 onward, a traditional IRA and 401(k) are pushing taxable income into the household whether it is needed or not. The years before RMDs are therefore the window for emptying high-bracket pots into lower-bracket years, either by drawdown or conversion.

The Currency Dimension

A UK pension drawdown is a GBP transaction that becomes USD income. The timing of conversion, the spot rate on the day, and the frequency of withdrawals all affect the dollar result. Currency considerations are covered in depth in a separate article in this series.

The UK 25% Element, When, in Which Year, on What Position

Because the US tax treatment of the UK 25%element is contested, the decision of whether to take it, when to take it, and how to document the US position is a piece of sequencing in its own right. Some households take it across multiple UK tax years; others take it as a single event. The answer turns on the household's other taxable income and the documented tax position with the US adviser.

How the US-UK Treaty and FTC Mechanics Shape Efficient Years

Under Article 17(1), UK pension income fora US resident is generally taxable in the US, not in the UK. Where UK tax is in fact withheld at source, Article 24 and Section 901 deliver credit relief. The practical consequence is that the year a UK pension distribution lands in often matters as much as the amount.

Two examples of the principle, kept high-level. A year where US passive-basket income is small offers little US tax to absorb FTC; UK tax paid in that year may carry forward without ever being used. A year where US ordinary income is being managed below the next bracket threshold offers the opposite problem: an additional UK drawdown can push the household over the threshold for no incremental benefit. Sequencing is, in part, the practice of avoiding both.

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An Educational Framework for Mapping a Sequence

The mapping work tends to follow five steps. None of them require specific recommendations; all of them require visibility on both sides of the Atlantic.

1. List every pot, with its US tax treatment, current balance, currency, and earliest access date.
2. Project household US ordinary income year by year from now to age 80, without yet adding pension or Roth conversion activity.
3. Identify the pre-RMD window, the years between the end of paid work and age 73, and the headroom inside each bracket each year.
4. Layer UK pension drawdown, the UK 25% element, traditional IRA withdrawals, and Roth conversions into the headroom, watching the FTC balance each year.
5. Re-run after every UK or US tax-law change, and at least annually.

An Illustrative Example

Consider a hypothetical UK-origin household in their mid-60s, retired, with a UK personal pension worth about £600,000, a traditional IRA of about $500,000, a Roth IRA of about $100,000, and a taxable brokerage account of about $200,000. Neither spouse has yet claimed US Social Security; both UK State Pensions are several years away.

A two-system sequence might use the taxable account and modest UK drawdown in the early years to fill lower US brackets while keeping FTC in balance. The UK 25% element might be staged across the lowest-bracket years with a documented US position. Roth conversions might fill any remaining bracket headroom, reducing the traditional IRA balance and therefore the eventual RMDs. As Social Security and the UK State Pension come on, the drawdown rate from each pot adjusts.

The numbers shift every year. The structure does not. Illustrative only; individual facts differ.

Questions To Raise With A Qualified Adviser

These are not recommendations. They are questions to take into a conversation with a cross-border adviser who understands both sides of the Atlantic.

• What is my projected US ordinary income year by year between the end of paid work and the start of RMD sat 73?
• How much bracket headroom exists each year, and how much of it is best filled by UK pension drawdown, traditional IRA withdrawal, or Roth conversion?
• What is my documented US tax position on the UK 25% element, and in which year(s) will it be taken?
• Is my FTC carryforward balance being tracked, and is my UK drawdown rate calibrated to use rather than strand it?
• When do I plan to claim US Social Security and the UK State Pension, and how does each claim age change the bracket picture?
• Which adviser owns the year-by-year sequencing model, and when is the next review scheduled?