Grammar Tuesdays (with Joanna): Don’t have to vs. Mustn’t


Do not have to (or don’t have to) means that you do not need to do something, but you can.

Must not (or mustn’t) means that you’re not allowed to do something. You cannot do it.


You don’t have to answer the bonus question. (You don’t need to answer it, but you can if you’d like.)

You mustn’t text and drive. (You’re not allowed to text while driving. / You can’t text while driving. It’s against the law.)

texting and driving

Try it. Choose don’t have to or mustn’t.

You _____________________________ help him with the project, but he’d appreciate it if you did.

Students ________________________ use calculators during the math test. They have to complete all calculations on paper.

We _____________________ enter this area. There is a sign that says “No trespassing.”

I ______________________ work on my paper today. It’s not due until next Friday. Let’s go to the beach!

Did you get it right? Here’s the answer key:

don’t have to / mustn’t / mustn’t / don’t have to


Joanna Rodzen-Hickey

Joanna Rodzen-Hickey has been an ESL teacher and consultant for nearly 20 years. She has taught English at numerous universities and community colleges in New Jersey and currently teaches at the Hackettstown High School in Hackettstown, NJ.

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