A claim on the SA109, not a default setting
HMRC's helpsheet HS266 is clear: relief under the foreign income and gains (FIG) regime only exists if you claim it on the SA109 pages of a Self Assessment return. Box 28 claims relief on foreign income, box 29 on foreign gains, and every amount you want relieved must then be reported source by source on the supplementary pages. The claim is strictly annual: claiming for 2025/26 does nothing for 2026/27, and you redo the decision, and the arithmetic, each year. Our SA109 walkthrough covers each box in detail.
Why doing nothing is expensive
With no claim, you are just a UK resident taxed on worldwide income, whatever your dates. And the window will not wait: it is fixed by your first year of UK residence and runs whether you claim or not. The regime only went live on 6 April 2025, so someone who arrived in 2023/24 can claim for just 2025/26 and 2026/27 before their four years are spent. There is a cost side too: each claim year forfeits your £12,570 personal allowance and £3,000 CGT annual exempt amount, so small claims are often not worth making.
You cannot file it on HMRC's free service
The last trap is practical. HMRC's own online filing service does not support the SA109, and the notes say not to attach it electronically to an online return, so your options are commercial software, an agent, or a paper return due earlier, by 31 October. And ticking the box is not enough: a claim that does not quantify the relieved amounts at all is invalid, so relieved never means left off the return. If you are unsure whether you qualify at all, start with our overview of the FIG regime.