Must, Have To, Mustn’t and Don’t Have To
Required. Prohibited. Optional.
By the end: Explain what someone needs to do, must avoid and can choose for themselves.
Tutor guide: Let the learner try first. Use the two follow-up prompts, then ask them to explain a quiz choice. Extra discussion is optional.
The quick answer
Must and have to express necessity or obligation. Mustn’t means something is prohibited. Don’t have to means it is not necessary. The negative forms have very different meanings: You mustn’t bring food forbids it; You don’t have to bring food says bringing it is not required.
You are helping a friend join a community workshop. Clear instructions should make the requirements and choices easy to understand.
Read the three short sections, use the speaking pauses, then check your understanding. The extra-detail panels are optional.
1. Mustn’t and don’t have to: different rules
Required
“You have to book a place.”
A booking is necessary. You cannot simply turn up without one.
Prohibited
“You mustn’t touch the equipment before the demonstration.”
This action is not allowed yet.
Optional
“You don’t have to bring tools. We provide them.”
Bringing tools is not necessary. This sentence does not prohibit bringing them.
| Meaning | Pattern | Example |
|---|---|---|
| Necessary | must / have to + base verb | You must book. You have to book. |
| Not allowed | must not / mustn’t + base verb | You mustn’t touch it. |
| Not necessary | don’t / doesn’t have to + base verb | You don’t have to bring tools. |
2. Choose must or have to, then check the form
Must: strong necessity
“I must remember my booking.”
The speaker presents this as important. Must also appears in official rules: Visitors must sign in.
Use must + base verb: She must arrive, not she musts arrive or must to arrive.
Have to: a requirement
“We have to arrive before ten.”
This often reports a practical requirement or someone else’s rule. It is very common in conversation.
She has to arrive.
Does she have to arrive early?
She doesn’t have to arrive early.
3. Questions, past rules and future needs
Ask naturally: Do we have to book? / Does Jo have to pay? Use have, not has, after does.
A past requirement
“Yesterday we had to wait outside.”
Use had to for past obligation. We didn’t have to wait means waiting was not necessary; it does not by itself tell you whether we waited.
A future requirement
“Next time we’ll have to arrive earlier.”
Will have to makes the future requirement explicit. We must arrive earlier tomorrow can also refer to a future obligation.
What about don’t need to and needn’t?
You don’t need to bring tools and You needn’t bring tools also express lack of necessity. They do not mean prohibition. Needn’t is particularly useful to recognise in British English.
Does must always express a rule?
No. You must be tired can express a conclusion from evidence. This lesson focuses on obligation. The separate Modals of Deduction lesson explains that other meaning.
Must can also be strong encouragement: You must try this cake! Context matters.
Welcome to the workshop
Tap a large phrase button to hear its example. Repeat it, then change one detail. Use the player for the complete recording.
Choose an example, or play the complete recording.
Voice: Amanda · 23 seconds · English (United States). Written lesson examples use British English conventions.
Listening focus: Listen. Name two requirements, one prohibition and one thing participants do not need to bring.
Read the full transcript
Welcome to the workshop. You have to book a place before you arrive. You must sign in at the desk. You mustn’t touch the equipment before the demonstration. You don’t have to bring your own tools. We provide everything you need. Do we have to stay all afternoon? No, you do not.
Check the listening answer
Requirements: book a place and sign in. Prohibition: touching the equipment before the demonstration. Participants do not need to bring their own tools.
Repair two messages
Say or write a corrected version first. Then open the explanation.
1. “You don’t have to use your phone. Phones are forbidden here.”
Show the correction and reason
You mustn’t use your phone. Phones are forbidden here.
A prohibition needs mustn’t here. Don’t have to would say phone use is not necessary.
2. “Does she has to book?”
Show the correction and reason
Does she have to book?
After does, use the base form have.
Mastery quiz
Choose one best answer for each situation. Work without the table first, then check all eight answers. Every choice has an explanation.
Answer key with explanations
Photographs are not allowed. Mustn’t expresses prohibition in this instruction.
Bringing lunch is not necessary. The sentence removes a requirement. It does not itself prohibit the action.
She has to wear a badge. Use has to with she in a present-simple statement.
Does he have to pay? Does + subject + have to + base verb is correct.
had to Had to expresses the past requirement.
Both can express obligation, and their uses sometimes overlap. The distinction is a tendency in presentation, not an absolute division.
You have to register, but you don’t have to buy a T-shirt. Have to gives the requirement; don’t have to removes the other requirement.
Waiting was not necessary. Didn’t have to describes no past necessity, not a definite account of what happened.
This checks understanding of this lesson. It does not assign an overall English level.
Use it without the model
Explain three rules for a place you know. Then change one rule from prohibited to optional and explain the new meaning.
If a form still feels uncertain, revisit its explanation and try a new example. You can return tomorrow for a quick recall check.