The Verdict: Clear Path
As an EU, EEA, Swiss or British citizen you need no permission to retire to Ireland, and the €50,000 Stamp 0 test does not apply to you. Arrange a PPS number and health cover, and get advice on how your pension is taxed, before you move.
British citizens live in Ireland under the Common Travel Area, with no conditions and with access to healthcare and social protection as residents. EU, EEA and Swiss citizens rely on free movement: after three months a retiree needs enough resources not to rely on social assistance, and sickness insurance. No figure is published for those resources; they are judged on your own circumstances.
There is no Stamp 0 and no annual renewal: those apply only to other nationalities.
Your residence counts towards naturalisation if you later want an Irish passport: five years in the last nine, with the final year continuous. Check first whether you are entitled already through a parent or grandparent born on the island of Ireland.