Tag questions in English represent a structure that, by being added to the preceding clause, questions or verifies its content. Despite their wide usage, little has been said about the grammatical source of tag questions. Tag questions are essentially divided into two classes; the regular tag (e.g., did/didn’t she?) and the cleft tag (e.g., is/isn’t it?). Among the two available types of tag, Barros & van Craenenbroeck (2013) extensively studied the tag preference, claiming that the cleft tag is the default one (named as Default Non-Isomorphism). By contrast, the results of our acceptability judgment tasks showed that the regular tag in fact is the favored one, with the use of the cleft tag being sensitive to the focused/adjacent element of the host clause. Namely, the cleft tag is preferred only when a sufficient amount of focus is present. This finding is empirically attested in assorted conditions involving the two types of tag questions. Examined conditions principally varied by the referent of the fragment answer preceding the tag question at stake (i.e., whether the fragment is referring to the subject or object of the forgoing sentence). In addition, the presence/absence of the polarity answer particle (i.e., yes or no) anteceding the tag question was tested.