Irish citizenship for Brits: the grandparent route

Millions of Brits have an Irish-born parent or grandparent, and plenty of them could hold an Irish passport without ever having thought about it.

The short version

Irish-born parent? If a parent was born on the island of Ireland (Northern Ireland included) and was an Irish citizen, or entitled to be, when you were born, you're probably already Irish. You just apply for a passport [1].
Irish-born grandparent? You can become Irish by entering your birth on the Foreign Births Register. It costs €278 for an adult (about £232) and takes about 12 months [1][2].
No Irish family? Living in Ireland for five years out of the last nine, including the final year, lets you apply for naturalisation. That costs €175 to apply and up to €950 if you're approved [3].
Dual citizenship is fine. The UK allows it, and you don't need to give up your British passport to become Irish [4].
An Irish passport makes you an EU citizen, which matters more for life in Spain or France than for life in Dublin, where British citizens already have Common Travel Area rights.

Pound conversions use the Bank of England spot rate of 5 November 2026 (£1 = EUR 1.2002), rounded.

Why bother, if the CTA already covers you?

For living in Dublin, the Common Travel Area gives you almost everything: the right to live, work, study, use public services and vote in general and local elections [5]. So why do so many Brits in Ireland apply?

EU citizenship. An Irish passport brings free movement across the EU and EEA. No 90/180-day rule, no visa for retiring to the Algarve, no Entry/Exit System queues.
Full voting rights in Ireland, including presidential elections and referendums, which UK citizens can't vote in [5].
Your children. If you're on the Foreign Births Register before a child is born, they can register too. If you're not, they lose that route [1][2].
Belonging. For many people it's about family history as much as paperwork.

Route 1: an Irish-born parent

Citizens Information sets out the rule: if you were born outside Ireland and either parent was born in Ireland and was an Irish citizen at the time of your birth, you're automatically an Irish citizen [1]. You don't register anything. You simply apply for an Irish passport with your parent's documents.

Northern Ireland counts. Someone born in Northern Ireland before 1 January 2005 is entitled to Irish citizenship [1]. Lots of British families have a parent born in Belfast, Derry or Newry who never thought of themselves as Irish. If that parent was entitled to be Irish when you were born, you may well be Irish already. Check with the Passport Service or the Immigration Service Delivery online checker if your case isn't clear-cut [1].

If your Irish parent was born outside Ireland (say, in Liverpool to Irish parents), you're not automatically Irish, but you're entitled to register on the Foreign Births Register [1][2].

Route 2: an Irish-born grandparent and the Foreign Births Register

If one of your grandparents was born on the island of Ireland but neither of your parents was, you can become Irish through Foreign Birth Registration [1][2]. Once you're on the register, you're an Irish citizen and can apply for a passport [2]. Your citizenship runs from the date you're registered, not from your birth [1].

	Adult (18+)	Under 18
Registration plus certificate	€270 (about £225)	€145 (about £121)
Postage and handling	€8	€8
Total	€278 (about £232)	€153 (about £127)

Fees from the Department of Foreign Affairs, paid online when you apply [2].

The documents

This is the faff part. For an adult applying through a grandparent, the Department of Foreign Affairs wants originals of [2]:

Your own civil birth certificate showing your parents' details, any marriage or change-of-name certificate, a certified copy of your photo ID, two proofs of address and four colour photos.
Your parent's (the one descended from the Irish grandparent) civil birth certificate, any marriage certificate, and a certified copy of their photo ID or their death certificate.
Your grandparent's civil birth certificate, any marriage certificate, and a certified copy of their photo ID or their death certificate.

Church baptism records won't do: it has to be the civil certificate. For a grandparent born in the Republic, order it from the General Register Office. For Northern Ireland births, it comes from GRONI.

Witnesses

The form and two of the photos must be signed by a witness who knows you personally and isn't a relative. The list includes police officers, teachers, clergy, doctors, nurses, pharmacists, solicitors, bank managers, accountants and elected representatives [2]. Your mate from the pub won't count unless he's also your GP.

How long it takes

Applications are processed in strict date order, and the Department said it was taking about 12 months when we checked in November 2026 [2]. You can't speed it up, but expectant parents can contact the Foreign Birth Registration helpline, because timing matters for them.

The great-grandparent problem

The chain stops after one link. If your parent didn't register before you were born, you can't claim through a great-grandparent [1]. That's why it's worth registering before you have children: a child born after you're on the register can then register in turn [1].

Route 3: naturalisation after living in Ireland

No Irish ancestors? Living in Ireland can get you there. Immigration Service Delivery (ISD), part of the Department of Justice, decides naturalisation applications, and the Minister has absolute discretion [3].

The main conditions [3]

You're 18 or over.
You've had one year of continuous residence immediately before you apply, plus four years in the eight years before that: five years out of nine in total.
In that final year you can spend up to 70 days outside Ireland, with up to 30 more for exceptional reasons such as illness or work.
You're of good character. The Gardaí provide a report, including driving offences.
You intend to keep living in Ireland.

The good news for Brits: UK citizens don't need an Irish Residence Permit, and all your periods of residence in Ireland count [3]. You don't send the reckonable residence calculation that non-EU applicants do. Instead you show your residence history with documents under ISD's scorecard system, which needs 150 points for identity and 150 for residence [3]. Payslips, tenancy agreements, Revenue statements and utility bills all help, so keep them.

Married to an Irish citizen?

You can apply after three years of marriage or civil partnership and three years' residence on the island of Ireland out of the last five, including the final 12 months. Here, legal residence in Northern Ireland counts too [3].

Fees and timescales [3]

Stage	Fee
Application	€175 (about £146)
Certificate if approved (most adults)	€950 (about £792)
Certificate for a minor, or a widow, widower or surviving civil partner of an Irish citizen	€200 (about £167)

Citizens Information says most applications are processed within 19 months [3]. If you're approved, you're usually invited to a citizenship ceremony to make a declaration of fidelity to the nation and loyalty to the State. You can't apply for an Irish passport until you have your certificate [3]. A refusal can't be appealed, but you can apply again [3].

Keeping both passports

The UK allows dual citizenship, and you don't need to apply for it: you can take another citizenship and stay British [4]. Ireland doesn't make you give up your British citizenship either. Many people in Northern Ireland hold both.

A few things to know:

Consular help. The FCDO says you can't get British diplomatic help in a country where you're also a citizen [4]. In Ireland, that means the British Embassy in Dublin can't step in for you as it would for a British-only citizen.
Travelling to the UK. As a dual British–Irish citizen you can enter the UK on either passport, and you don't need an ETA [4].
Your British passport. Keep renewing it if you want it. Our guide to renewing a British passport from abroad explains how.
Children born in Dublin. A child born in Ireland to a British or Irish parent is automatically Irish [1]. Whether they're also British depends on how you got your British citizenship. Our guide to registering a child born abroad covers citizenship by descent.

If you've been through the Foreign Births Register and want to share what tripped you up, our community group for Brits in Ireland is here.

Irish citizenship for Brits: grandparents, the Foreign Births Register and naturalisation