Question tags are used in English to encourage someone to carry on talking. We use these question tags when we want to ask a question, or if we want someone to agree with us.
She doesn't like swimming, does she?
(No, she doesn't.)
He can't cook, can he?
(No he can't.)
He's interesting, isn't he?
(Yes, he is.)
We've been here before, haven't we?
# How to make question tags
To make a question tag in English, use the auxiliary verb (if there is one) in the sentence.
She doesn't like… (doesn't is the auxiliary)
He can't cook… (can't is the auxiliary)
He's interesting… (is is the auxiliary)
We've been here… (have is the auxiliary)
# Negative and positive tags
If the auxiliary is negative, the tag is positive.
She doesn't like…
If the auxiliary is positive, the tag is negative.
# No auxiliary?
If there isn't an auxiliary in the verb, use the right form of 'do' instead.
He likes tennis, doesn't he?
You saw her last week, didn't you?
We don't know that for a fact, do we?
Source : english-at-home