Living there is easy; tax residence is a separate question
Nothing stops a UK taxpayer living in Ireland. The Common Travel Area lets you move freely between the two countries, and once you are non-UK resident under the Statutory Residence Test your worldwide income generally leaves the UK net and is taxed where you now live. The point people miss is that the Common Travel Area has no bearing on tax. HMRC applies the SRT, set out in guidance note RDR3, in three stages: the automatic overseas tests (fewer than 16 UK days, or full-time work abroad within the detailed conditions), then the automatic UK tests (183 days or more), then the sufficient ties test, which weighs your UK days against family, accommodation, work and time spent here in earlier years. Days count on a midnight basis, so you are effectively counting nights. Our Statutory Residence Test guide walks through the day counts and ties.
The year you leave, and the trap if you come back
Split-year treatment can divide the year you move into a UK part and an overseas part, so income arising after you leave is generally outside UK tax. It is not automatic and not a free choice: you must fall within a specific SRT case, such as starting full-time work overseas or ceasing to have a UK home while taking up residence abroad, and the case fixes the date your overseas part begins. You claim it on the SA109 residence pages. Because Dublin is so close, the temporary non-residence rule is a real risk. If you were UK resident in at least 4 of the 7 tax years before leaving and your period of non-residence is 5 years or less, gains and certain income realised while away are taxed in the year you return. Escaping it generally needs 5 full tax years plus a split year, or 6 full tax years. See our split-year treatment guide.
What the UK keeps taxing after you move
Leaving does not switch off UK tax on UK-source items. Rent from a UK property stays fully taxable: your letting agent, or a tenant paying rent direct above the threshold, deducts 20% under the Non-Resident Landlord Scheme unless HMRC approves gross payment on form NRL1, and you still file a UK return with the SA105 and SA109 pages. Sell UK property as a non-resident and you must report the disposal and pay any tax within 60 days of completion, even where no tax is due. Pay for duties physically performed in the UK often remains taxable. Pensions turn on the 1976 UK-Ireland treaty: most occupational and private pensions become taxable only in Ireland, while government-service pensions usually stay UK-taxable unless you are an Irish or dual national. Ireland has its own residence rules and a remittance basis for non-Irish-domiciled residents, which a local adviser should confirm. Our moving to Ireland guide has the full checklist.