How are RSUs taxed if they vest after I move to the UK?

Equity that was granted before your move but vests after it is generally divided between the US and the UK, rather than taxed entirely by one country. The usual approach apportions the award by how much of the period from grant to vest fell on each side of the move. The precise basis for that split is fact-specific and set by each country's rules and the treaty. (Source: US–UK Income Tax Convention (2001), Article 14; HMRC ERSM160000 (rule module shared/apportionment@1.0.0).)

Does the whole RSU get taxed twice?

The point of apportioning the award, and of the US–UK treaty, is to avoid the same slice of income being taxed in full by both countries. Each country taxes the portion attributable to it, with treaty relief coordinating the overlap. How the portions are measured (for example, by calendar days or by workdays) is exactly the detail that decides the numbers, so it is worth confirming for your grant. (Source: US–UK Income Tax Convention (2001), Article 14; OECD Model Article 15 commentary (rule module shared/apportionment@1.0.0).)

Field Guide

What Happens to RSUs That Vest After You Move to the UK

Rules as of 2026-07-04 · shared/apportionment@1.0.0

Field Guide · Two Shores · twoshores.app

Educational information, not tax or investment advice. Rules described as of the 2026 tax year; always confirm current law or consult a professional for your situation.

If you are paid partly in RSUs, the move gives you a timing problem you did not choose. A grant made while you were working in the US often vests months or years later, and by then you may be living in the UK. Neither country wants to ignore that income, so the usual result is not "the US taxes it" or "the UK taxes it," but a split.

Why RSUs get divided between two countries

An RSU is really compensation for the period between grant and vesting. When that period straddles your move, both countries have a claim on the part of the reward that was "earned" while you were connected to them. The common approach is to apportion the award across the vesting period and attribute each part to where you were during it. The Two Shores engine models this on a calendar-day basis and labels the result as illustrative, precisely because the statutory basis, including whether workdays rather than calendar days are the correct measure, is pending independent review.

The detail that decides the numbers

The headline idea (split the grant across the move) is simple. The number is not, because it turns on the measurement rule: the relevant period, whether to count calendar days or workdays, how each country sources the income, and how the US–UK treaty Article 14 and the OECD commentary interact. Those are cited in the engine and flagged for a reviewer rather than asserted here, so treat any worked figure as an illustration until it is confirmed for your grant.

What people in this position usually do

People with vesting RSUs across a move commonly: list each grant with its grant and vest dates, see an illustrative split so they understand the shape of the exposure, and then confirm the correct apportionment basis with a professional before relying on a number, especially for large grants where the difference between methods is real.

The US to UK Move Playbook draws each grant across your move date as an illustration. See also how the UK decides if you are tax-resident, which sets the dates the split hinges on.

Common questions

How are RSUs taxed if they vest after I move to the UK?: Equity that was granted before your move but vests after it is generally divided between the US and the UK, rather than taxed entirely by one country. The usual approach apportions the award by how much of the period from grant to vest fell on each side of the move. The precise basis for that split is fact-specific and set by each country's rules and the treaty.Source: US–UK Income Tax Convention (2001), Article 14; HMRC ERSM160000 (rule module shared/apportionment@1.0.0)
Does the whole RSU get taxed twice?: The point of apportioning the award, and of the US–UK treaty, is to avoid the same slice of income being taxed in full by both countries. Each country taxes the portion attributable to it, with treaty relief coordinating the overlap. How the portions are measured (for example, by calendar days or by workdays) is exactly the detail that decides the numbers, so it is worth confirming for your grant.Source: US–UK Income Tax Convention (2001), Article 14; OECD Model Article 15 commentary (rule module shared/apportionment@1.0.0)