An EEA National, who stays in Hungary not more than 90 days (within any consecutive 180 days), does not need to comply with any immigration formalities. However, he/she needs to make sure that his/her travel document (passport or ID card) by which he/she crossed the Hungarian border remains valid throughout his/her entire stay in Hungary.
If during the Hungarian stay, this EEA National intends to work for an Organisation seated in Hungary, this Hungarian Organisation might have immigration and working authorisation related notification obligations towards the Hungarian authorities. For further information on these notification obligations please see: Notifications as Employer's obligation.