In order to work in Ireland, an Irish social registration number ( “PPS number” from Personal Public Service) is required.

You can obtain it very easily by contacting a Tax office. This number is mandatory and you need it as soon as possible to avoid paying Emergency taxes.
It allows you to open a bank account and to have the social cover and the Irish retirement ("PRSI" for Pay Related Social Insurance).

This social protection partly covers unemployment, pension, disabilities and some of the medical care. However, a complete protection can be obtained using complementary mutual insurance companies (the principal insurers are VHI and VIVAS) generally taken by the employers.