You can keep and later roll over your U.S. retirement accounts after returning to the UK, but keep pretax money out of IRAs through your final backdoor-Roth year and complete any deliberate Roth conversion before UK residence begins if you want the clearest tax result.

Articles 17(1)(a)–(b) and 18

Pensions and other similar remuneration beneficially owned by a resident of a Contracting State shall be taxable only in that State. Notwithstanding sub-paragraph a) of this paragraph, the amount of any such pension or remuneration paid from a pension scheme established in the other Contracting State that would be exempt from taxation in that other State if the beneficial owner were a resident thereof shall be exempt from taxation in the first-mentioned State. Where an individual who is a resident of a Contracting State is a member or beneficiary of, or participant in, a pension scheme established in the other Contracting State, income earned by the pension scheme may be taxed as income of that individual only when, and, subject to paragraphs 1 and 2 of Article 17 (Pensions, Social Security, Annuities, Alimony, and Child Support) of this Convention, to the extent that, it is paid to, or for the benefit of, that individual from the pension scheme (and not transferred to another pension scheme).

Articles 3 and 17

In the case of the United States, the term ‘pension scheme’ includes the following: qualified plans under section 401(a), individual retirement plans (including individual retirement plans that are part of a simplified employee pension plan that satisfies section 408(k), individual retirement accounts, individual retirement annuities, section 408(p) accounts, and Roth IRAs under section 408A). 401(k) plans qualify as pension schemes because a 401(k) plan is a type of 401(a) plan. Thus, for example, a distribution from a U.S. ‘Roth IRA’ to a U.K. resident would be exempt from tax in the United Kingdom to the same extent the distribution would be exempt from tax in the United States if it were distributed to a U.S. resident.

A particular feature of the UK/US DTA is that, although paragraph 2 of Article 17 gives exclusive taxation rights over lump sum payments to the State in which the payment arises, this is in effect overridden by paragraph 4 of Article 1. The effect of paragraph 4 of Article 1 is that the DTA will not prevent either State from taxing its own residents unless the provision is specifically listed in paragraph 5 of Article 1. This means that although the State in which the pension lump sum arises will be able to tax that payment under Article 17, the State in which the recipient is resident will also be able to tax the payment under Article 1. Relief from double taxation will be available under the treaty in the usual way.

Direct rollover

Direct rollover – If you’re getting a distribution from a retirement plan, you can ask your plan administrator to make the payment directly to another retirement plan or to an IRA. Contact your plan administrator for instructions. The administrator may issue your distribution in the form of a check made payable to your new account. No taxes will be withheld from your transfer amount.

Earnings associated with after-tax contributions are pretax amounts in your account. Thus, after-tax contributions can be rolled over to a Roth IRA without also including earnings.

Line 6

Enter the total value of all your traditional IRAs as of December 31, 2025, plus any outstanding rollovers.

Chapter 2, Roth IRAs

You don't include in your gross income qualified distributions or distributions that are a return of your regular contributions from your Roth IRA(s).

Therefore, if you roll over a designated Roth account to a Roth IRA, the period that the rolled-over funds were in the designated Roth account does not count towards the 5-taxable-year period for determining qualified distributions from the Roth IRA. However, if you had established a Roth IRA in a prior year, the 5-year period for determining qualified distributions from a Roth IRA begins with the earlier contribution.

You may be able to leave your account where it is.

Pensions, annuities, and alimony

Generally, pension and annuity payments are subject to 30% withholding. A treaty may exempt the entire pension from tax.

Give Form W-8BEN to the withholding agent or payer if you are a foreign person and you are the beneficial owner of an amount subject to withholding. Do not send Form W-8BEN to the IRS.

Residency termination date

Generally, your residency termination date is December 31 of the year you cease to be a U.S. resident. However, your residency termination date will be the last day during the calendar year that you are physically present in the United States if, for the remainder of the calendar year, your tax home was in a foreign country and you maintained a closer connection to that foreign country than to the United States.

Long-term resident

You are a long-term resident (LTR) if you were a lawful permanent resident of the United States in at least 8 of the last 15 tax years ending with the year your residency ends.

Your residence status when you move

When you move in or out of the UK, the tax year is usually split into 2 - a non-resident part and a resident part. This means you only pay UK tax on foreign income based on the time you were living here. This is called ‘split-year treatment’.

2026 limit

For 2026, your total contributions to all of your traditional IRAs and Roth IRAs cannot be more than: $7,500 ($8,600 if you're age 50 or older), or If less, your taxable compensation for the year. Rollovers and qualified reservist repayments are not included in this limit.