Main clause in red here: I don't think that it will rain tomorrow, do you? He said that it will rain tomorrow, didn't he? EXPLANATION: I don't think is the main clause. But because it expresses the speaker's opinion -- or, actually, signals that the speaker is about to express an opinion in the subordinate clause -- the tag does NOT go on the main clause in this case. The tag is not about whether it will rain but about whether the listener agrees with the speaker. In my second example, the main clause is He said. This is not an expression of opinion but a statement of another's opinion. The tag is on the main clause, asking for confirmation that he said that. Okaasan, Co-Moderator (A native-speaking American with a Japanese nickname, living in Egypt) http://thegrammarexchange.infopop.cc/eve/forums/a/tpc/f/340600179/m/418109924