Question tags turn a statement into a question by adding a short phrase at the end. The trick is simple: the auxiliary verb in your tag must match the auxiliary verb in your sentence.
If someone says "She's gone out," you add a tag using the same auxiliary. "Has gone" is the auxiliary, so the tag is "hasn't she?" Not "doesn't she" or "isn't she". The auxiliary you hear in the sentence is the one you echo in the tag, inverted and usually negative if the original was positive.
What Exactly is a Question Tag?
A question tag is a mini question you attach to the end of a statement to invite agreement or check information. English speakers use them constantly in real conversation. "You're coming to dinner, aren't you?" "He didn't call, did he?" "They've finished the project, haven't they?" The tag turns a statement into a request for confirmation.
Why the Auxiliary Verb Matters
The auxiliary verb is the helping verb that carries the grammar. In "she's gone out," the auxiliary is "has". In "you're staying late," it's "are". In "they don't know," it's "do". When you write your tag, you must use the same auxiliary, not a different one. This is where most learners get stuck. You hear "has gone" and want to reach for "does", but that breaks the rule. The tag needs "has".
How to Build a Question Tag: The Pattern
Take the auxiliary from the sentence. Flip it to the opposite (positive becomes negative, negative becomes positive). Add the pronoun. That is your tag.
Example: "She's gone out." Auxiliary is "has". Flip it to negative: "hasn't". Add the pronoun "she": "hasn't she?" Full sentence: "She's gone out, hasn't she?"
Another example: "They haven't arrived." Auxiliary is "have". Flip it to positive: "have". Add the pronoun "they": "have they?" Full sentence: "They haven't arrived, have they?"
One more: "You can swim." Auxiliary is "can". Flip it to negative: "can't". Add the pronoun "you": "can't you?" Full sentence: "You can swim, can't you?"
Common Auxiliaries and Their Tags
Be (am, is, are, was, were): "He's tired, isn't he?" "They were late, weren't they?"
Have (have, has): "She's finished, hasn't she?" "We've done it, haven't we?"
Do (do, does, did): "You like coffee, don't you?" "He works here, doesn't he?" "They left early, didn't they?"
Modals (can, could, will, would, should, must): "You can help, can't you?" "She will come, won't she?" "They should know, shouldn't they?"
Where to Practice This With Real People
Grammar rules stick when you use them in actual conversation. Reading about question tags is one thing. Hearing them, asking them, and getting corrected by a native speaker is another. When you speak with someone who uses English every day, you hear the natural rhythm of when these tags come up and how they sound.
PBC Languages is an online language community where you can do exactly that. They offer free language exchanges with native English speakers, so you can practice question tags in real dialogue with no app between you. You also get small group classes, maximum four students, which means you actually get speaking time and feedback instead of sitting silent in a large room.
The first class is free. You can also join a free tandem exchange right away if you want to start speaking immediately. The WhatsApp groups keep you practising between classes so the grammar stays fresh.
Make It Stick
Question tags are not something you master once and finish. The more you speak, the more you notice them. Every time you hear or use one, you reinforce the pattern. Language lives in conversation, not in rules. Show up regularly to speak with real people, and question tags become natural.