Irish Citizenship by Descent Guide for UK Citizens 2026
Practical 2026 guide for British citizens claiming Irish citizenship by descent: Irish-born parent and grandparent eligibility, Foreign Births Register (FBR), required documents, current fees and processing times, EU citizenship rights and Common Travel Area benefits.
1. Executive Summary & Post-Brexit EU Passport Pathway
Irish citizenship by descent can allow eligible British citizens with an Irish parent or grandparent to become Irish citizens. Once Irish citizenship is established, the person is also an EU citizen and can exercise the rights attached to EU citizenship, including the right to move and reside in other EU Member States subject to the applicable EU free-movement rules.
2. Irish Citizenship Eligibility Matrix
The table below outlines eligibility paths based on Irish family lineage:
| Lineage Connection | Born Location | Citizenship Status | Application Required |
|---|---|---|---|
| Irish Parent Born in Ireland | Parent was born on the island of Ireland and was an Irish citizen when you were born | Irish citizen automatically if you were born outside Ireland | No FBR required; apply for an Irish passport once you have the required citizenship evidence |
| Grandparent Born in Ireland | Grandparent was born on the island of Ireland; applicant and parent were born outside Ireland | Can become Irish through Foreign Birth Registration | Complete FBR and be entered on the register before applying for an Irish passport |
| Parent Became Irish Before Your Birth | Parent became Irish through FBR or naturalisation before you were born | May qualify through Foreign Birth Registration | FBR required; the precise parentage/citizenship chain must be evidenced |
| Great-Grandparent Alone | Only a great-grandparent is Irish-born | No direct entitlement to FBR solely from a great-grandparent | An intermediate parent generally needs to have become an Irish citizen before the applicant's birth for the descent chain to operate |
3. Foreign Births Register (FBR) Process, Documents & Current Fees
Apply online through Ireland.ie and then send the required supporting documents to the Foreign Birth Registration service. Current adult applications can require the applicant's original civil birth certificate, certified photographic ID, two original proofs of address, witnessed photographs, and the corresponding civil and identity documents for the Irish citizen parent and Irish-born grandparent. The current FBR fee is €278 for adults and €153 for under-18s, and the published processing time is approximately 12 months for a completed application.
4. Common Travel Area (CTA) Rights Between UK & Ireland
Under the UK-Ireland Common Travel Area, Irish citizens in the UK do not need UK immigration permission, including a visa, residence permit or employment permit, to live and work in the UK. CTA rights also cover study, healthcare, social security and voting in certain elections, subject to the detailed rules applicable to each right. Narrow exceptions apply, including certain deportation orders, exclusion decisions and international travel bans.
Essential Summary & 2026 Checklist
- If your parent was born in Ireland, you are automatically an Irish citizen.
- If a grandparent was born in Ireland, register on the Foreign Births Register (FBR) to claim citizenship.
- Irish citizenship gives EU citizenship and the associated EU rights to move and reside in other EU Member States under the applicable EU rules; an Irish passport is evidence of Irish citizenship but is not itself the source of the citizenship rights.
- Dual British and Irish citizenship is 100% legal in both countries.
- Under the Common Travel Area, Irish citizens generally have the right to enter, reside and work in the UK without UK immigration permission, subject to narrow statutory exceptions.
Frequently Asked Questions (6)
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