Basic structure

A question tag takes a positive or negative form depending on the speaker's expectation.

If the speaker expects a negative response, he or she will use a negative statement with a positive tag.

Examples:

• We don't have a test today, do we?
• You haven't graduated yet, have you?

If the speaker expects a positive response, he or she will use a positive statement with a negative tag.

Examples:

• We have a test this afternoon, don't we?
• This is Wednesday, isn't it?

Notice that if there's no BE verb in the statement, you must at DO to the tag question.