Worldwide taxation, softened by the FIG window
UK residents are taxable on worldwide income and gains wherever they arise, which is the headline shift for anyone arriving from a Gulf state that taxed none of it. The 4-year FIG regime is the counterweight: qualifying new residents can claim 100% relief on foreign income and foreign gains for up to their first four tax years of residence, and relieved money can be brought into the UK freely. The gateway is strict. You must be within your first four years of UK residence following at least 10 consecutive tax years of non-UK residence, judged under the Statutory Residence Test, and a single UK-resident year in that period, a short assignment home for instance, breaks the condition. A returning British expat qualifies on the same footing as a first-time arrival, but each claim year forfeits your personal allowance and CGT annual exempt amount, so the claim is worth making only where the relieved amounts are substantial.
Plan before you land
The best planning happens while you are still non-resident; the options narrow sharply once you arrive. Gains crystallised before UK residence begins are generally outside UK CGT altogether, subject to the temporary non-residence rules if your absence was five years or fewer, in which case gains on pre-departure assets and close-company dividends drawn while away can be taxed in your year of return. Document market values of your assets at arrival, keep pre-arrival clean capital in a separate, clearly identified account so it can be brought in without a charge, and time your arrival against the 6 April tax-year boundary, since split-year treatment can limit the UK-taxed part of your arrival year. Note that selling UK residential property while still abroad has its own 60-day reporting duty regardless of everything above.
Old money and your estate
Wealth accumulated before 6 April 2025 needs separate handling if you previously used the remittance basis: those historic foreign income and gains still carry latent remittance exposure, and the Temporary Repatriation Facility lets you designate them at a flat 12% for 2025/26 and 2026/27, rising to 15% for 2027/28, after which the designated capital can be remitted freely. On death, inheritance tax is now residence-based: your worldwide estate comes into scope once you have been UK resident for at least 10 of the previous 20 tax years, with only UK-situated assets exposed before that, and a 3 to 10 year tail after any later departure. Horizon manages Gulf returns end to end, from FIG eligibility to TRF designations, on fixed fees agreed upfront, and a free clarity call several months before you fly is the single most valuable step you can take.