The present study, situated in the area of variational pragmatics, contrasts tag question (TQ) use in Ireland and Great Britain using spoken data from the Irish and British components of the International Corpus of English (ICE). Analysis is on the formal and functional level and also investigates form-functional relationships. Findings reveal many similarities in the use of TQs across the varieties. They also point, however, to a lower use of TQs in Irish English and in a range of variety-preferential features on both the formal and functional levels. The paper shows how an in-depth analysis of form-function relations together with a fine-tuned investigation of sub-functions gives an insight into formal preferences.