Under the old regime, UK-resident non-doms could elect the remittance basis and keep non-UK income and gains outside UK tax until brought (remitted) into the UK. From 6 April 2025 this was replaced by a four-year foreign income and gains (FIG) regime: new arrivals who have been non-UK-resident for the prior ten years get up to four years of UK tax exemption on foreign income and gains, after which worldwide taxation applies.
The change also reshaped IHT, moving from a domicile test toward a long-term-residence test (broadly, ten of the last twenty tax years). For property buyers this matters because the planning that once sheltered an offshore-held UK home has largely closed, and the cost of UK residence for internationally mobile families has risen.
Anyone relocating to the UK, or already here on the old basis, should take current advice — transitional rules apply to pre-2025 foreign income, gains and trusts, and the detail is still bedding in.