The A1 certificate shows which social insurance system a person belongs to. The A1 certificate must be attached when ordering cards for an EU Citizen posted from a foreign company. The employee will get the certificate from the local authority in his/her homeland and the certificate shows that the employee already belongs to another social insurance system and therefore should not pay tax for social fees in Sweden. The A1 certificate is mandatory when an EU Citizen employed in a foreign company applies for an ID06 card.