Until you break UK residence, nothing changes
The UK taxes residents on their worldwide income, so Malaysia's territorial system only becomes yours once you are non-resident under the Statutory Residence Test. Movers with a job aim for the full-time work abroad test: fewer than 91 UK days and no more than 30 UK workdays. Retirees on MM2H cannot use that test, so they fall back on the sufficient ties test, where a kept UK home makes summer visits the pressure point. Leave part-way through a tax year and split-year treatment can tax you as non-resident from your departure date, claimed on the SA109 pages of your Self Assessment return.
What stays UK-taxable after you leave
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 any tax paid within 60 days of completion, and the State Pension and UK government service pensions stay UK-taxable for most British movers. The five-year trap deserves particular respect in this corridor: if you were UK resident in at least four of the seven tax years before leaving and return within five years, the temporary non-residence rules tax gains realised abroad in your year of return, and because Malaysia charged nothing on them there is no credit to soften the landing. The residence-based inheritance tax tail can also run for up to 10 years after departure, with no Malaysian estate taxes to credit against it.
The Malaysian side: territorial, exempt and pension-friendly
Malaysia taxes income accruing in or derived from Malaysia, with resident rates rising to 30%. Foreign income received in Malaysia by resident individuals is largely exempt until 31 December 2036, individuals pay no general capital gains tax outside Malaysian real property, and there are no inheritance, estate or gift taxes. The prize is the pension article: under Article 19 of the 1996 UK-Malaysia treaty, UK occupational and personal pensions paid to a Malaysian treaty resident are taxable only in Malaysia, which currently exempts them, though the treaty's remittance clause means the money should actually be routed into Malaysia. Salary for work physically done in Malaysia is Malaysian-source and taxed at ordinary rates, so remote workers sit less comfortably than retirees. For the MM2H tiers, the personal allowance quirk and the full treaty position, see our guide to UK tax when moving to Malaysia. Horizon handles the UK side of the move on a fixed fee agreed upfront, and a free clarity call at /book will tell you what a clean exit looks like.