Foreign Birth Registration - Guidelines for Applicants
You are automatically an Irish citizen if one of your parents was an Irish citizen and was born in Ireland. You don’t need to apply to become an Irish citizen in this case.
If you were born outside of Ireland, you can become an Irish citizen if:
In these cases, you can become an Irish citizen through Foreign Birth Registration.
Once a person is entered onto the Foreign Births Register they are an Irish citizen and entitled to apply for an Irish passport.