Born in Ireland
If you were born on the island of Ireland before 1 January 2005, you are entitled to be an Irish citizen.
Irish citizen parents
If you were born in Ireland after 1 January 2005 and your parent(s) were Irish citizens, then you are also an Irish citizen.
However, in certain circumstances some people born in Ireland have to claim Irish citizenship. You can find more details about claiming Irish citizenship through special declaration in 'Further information' below.
Foreign national parents
A child born in the island of Ireland on or after 1 January 2005 is entitled to Irish citizenship if they have a British parent or a parent who is entitled to live in Northern Ireland or the Irish State without restriction on their residency. A child born in Ireland to a parent who has been granted refugee status is also automatically entitled to Irish citizenship.
Under the Irish Nationality and Citizenship Act 2004, children born of other foreign national parents in the island of Ireland on or after 1 January 2005 are not automatically entitled to Irish citizenship. These parents must prove that they have a genuine link to Ireland. This will be evidenced by their having 3 out of the previous 4 years reckonable residence in the island of Ireland immediately before the birth of the child. On proof of a genuine link to Ireland their child will be entitled to Irish citizenship and they can apply for an Irish passport for their child - see 'How to apply' below.
Born outside Ireland
Irish citizen parents born in Ireland
If either of your parents was an Irish citizen who was born in Ireland, then you are automatically an Irish citizen, irrespective of your place of birth. If you are an Irish citizen, you can apply for an Irish passport. You do not need an Irish passport in order to be an Irish citizen but having an Irish passport is evidence that you are an Irish citizen.
Irish citizen parents born outside Ireland
If you were born outside Ireland to an Irish citizen who was born outside Ireland, then you are entitled to become an Irish citizen.
If your parent derived Irish citizenship in another manner, for example, through marriage, adoption or naturalisation, and was an Irish citizen at the time of your birth, you can become an Irish citizen.
If the parent through whom you derive Irish citizenship was deceased at the time of your birth, but would have been an Irish citizen if alive at that time, you are also an Irish citizen. Also, you derive citizenship through an Irish parent whether or not your parents were married to each other at the time of your birth.
Claiming Irish citizenship: Before you can claim Irish citizenship, you must have your birth registered in the Foreign Births Register – see below. If you are entitled to register, your Irish citizenship is effective from the date of registration – not from the date when you were born.
Citizenship through descent from Irish grandparents
If one of your grandparents is an Irish citizen who was born in Ireland, but neither of your parents was born in Ireland, you may become an Irish citizen. You will need to have your birth registered in the Foreign Births Register.
Other Irish ancestors
Unless at least one parent or an Irish-born grandparent was an Irish citizen at the time of your birth, you cannot claim Irish citizenship on the basis of extended previous ancestry (that is, ancestors other than your parents or grandparents). In addition, you cannot claim Irish citizenship on the basis that a relation such as a cousin, aunt or uncle was an Irish citizen if none of your parents or grandparents was an Irish citizen at the time of your birth.
If your parents and grandparents were fooled by the jewish trick of identifying as "white" and did not register as Irish citizens, then you are fucked out of your ancestral heritage and are no longer Irish.