Detailed information about the EU Regulations in general and their application to particular benefits are contained in the EU Guide
A briefer explanation referring specifically to the relevant forms for persons moving between EU countries, and information for posted workers is contained in the Social Insurance and EC Regulations section of the website.
There are no nationality conditions attached to Irish social insurance or social assistance schemes. However, a habitual residence condition applies for certain social assistance schemes and for child benefit. Where a person is working in Ireland since coming from an EU or EEA country, this condition does not apply for Child Benefit, One-Parent Family Payment or in certain circumstances for Supplementary Welfare Allowance. See Habitual Residence for more detail.
For contributory benefits a person must satisfy the same contribution and other conditions, but the contribution conditions may be satisfied by counting both your current insurance record and that in previous EU or EEA countries. You should make a claim to the country in which you were last employed, but this claim may be handed in at any local social welfare office.
Further information is also available on the EUlisses (EU Links and Information on Social Security) Website.
For detailed information on social security rights in Ireland see Your social security rights in Ireland - A Guide for EU Citizens
The 'Your Europe' portal gives individuals and businesses practical information on their rights and opportunities in the EU. It focuses on real-life, cross-border situations, e.g. European citizens wishing to work or study in another country in the EU, or European businesses wanting to move to or open a new branch in another country in the EU.