Until you break UK residence, nothing changes
The UK taxes residents on worldwide income, so a move to South Africa only helps once you are non-resident under the Statutory Residence Test. Workers target the third automatic overseas test: full-time work abroad averaging at least 35 hours a week, fewer than 91 UK days and no more than 30 UK workdays. Retirees cannot use that route and usually fall into the sufficient ties test, where long summers back with family are exactly how a first non-resident year fails. If you leave mid-year, split-year treatment can tax you as non-resident from your departure date, claimed on the SA109 pages of your final return. One corridor quirk: the South African tax year runs from 1 March, so your split UK year and first SARS year never line up.
What stays UK-taxable, and what moves to SARS
Non-residents still pay UK tax on UK-source income. Rental profits fall under the Non-Resident Landlord Scheme, gains on UK property must be reported and paid within 60 days of completion, and government service pensions stay UK-taxable under the treaty unless you are both resident in and a national of South Africa. Most other UK pensions and annuities go the other way: Article 17 of the 2002 convention, in force since 17 December 2002 and amended by a 2010 protocol, makes them taxable only in South Africa once you are treaty-resident there, so a claim to HMRC can stop UK PAYE altogether. The UK State Pension is payable there but frozen at the rate in payment when you move, because South Africa has no qualifying uprating agreement.
The South African side, and the tails to plan around
SARS makes you resident if South Africa is your ordinarily resident home, or under the physical presence test built on 91-day and 915-day counts. Residents pay 18% to 45% on worldwide income, softened by rebates that keep roughly the first ZAR 99,000 out of tax, a capital gains regime that includes only 40% of a gain so the top effective CGT rate is 18%, and local interest exemptions that do not cover UK interest. On the UK side, two tails remain: return within five years and the temporary non-residence rules can tax gains you realised while away, and the residence-based IHT rules can keep a long-term UK resident's worldwide estate within UK IHT for up to 10 years. The full corridor detail is in our South Africa guide. Horizon handles the UK exit on fixed fees agreed upfront, and a free clarity call will tell you where you stand before any work starts.