Must and have to
Rules and duties with must and have to, mustn't or don't have to, had to, and need to.
Not sure A2 is your level? Find out in 8–40 questions, no account needed.
We use must and have to to say that something is necessary. In the negative they mean very different things: mustn't means "don't do it", but don't have to means "it isn't necessary".
Form
Must is like can: the same for every person, with no to after it. Have to is a normal verb: has to after he, she, it, and do or does in questions and negatives.
must | have to | |
|---|---|---|
positive | I must go. | She has to go. |
negative | You mustn't go. | He doesn't have to go. |
question | Must I go? | Do we have to go? |
- I must call my mother tonight.
- Nurses have to work at night sometimes.
- Incorrect: I must to finish this report today.
- Correct: I must finish this report today.After must, the verb has no to.
- Incorrect: She have to wear a uniform.
- Correct: She has to wear a uniform.
Must or have to?
In positive sentences both are possible, and the difference is often small. In British English, must often shows that the speaker thinks something is necessary. Have to is common for rules and situations that come from outside.
- I must go to the gym more often.
(It's my own idea.)
- I have to wear a helmet at work.
(It's a rule.)
- You must see that film. It's brilliant.
(A strong recommendation.)
In questions, Do I have to ...? is much more common than Must I ...?
- Do I have to book a table?
Mustn't: it's not allowed
Mustn't (must not) says that something is not allowed, or that it is a very bad idea.
- You mustn't use your phone in the exam.
- We mustn't be late for the train.
- You mustn't tell anyone. It's a secret.
Don't have to: it isn't necessary
Don't have to says that something is not necessary. You can do it if you want, but there is no need.
- You don't have to bring anything. We've got lots of food.
- It's Saturday, so I don't have to get up early.
- She doesn't have to work on Fridays.
mustn't | don't have to |
|---|---|
Don't do it. | You can do it, but it isn't necessary. |
You mustn't park here. | You don't have to pay. It's free. |
- Incorrect: You mustn't come to the meeting if you're busy. It isn't important.
- Correct: You don't have to come to the meeting if you're busy. It isn't important.Coming is not necessary. It is not against the rules, so mustn't is wrong here.
- Incorrect: You don't have to touch the oven. It's very hot.
- Correct: You mustn't touch the oven. It's very hot.This is a warning: don't do it.
Need to, don't need to, needn't
Need to is like have to. Don't need to and needn't mean the same as don't have to. Needn't is British and a little formal, and has no to after it.
- Do I need to print the ticket?
- You don't need to print it. You can show it on your phone.
- You needn't wait for me.
Past and future: had to, will have to
Must has no past form. For the past, use had to. For the future, use will have to.
- I had to work late yesterday.
- Did you have to pay for parking?
- We didn't have to wait long.
- You'll have to take a taxi. There are no buses after midnight.
- Incorrect: I must work last Saturday.
- Correct: I had to work last Saturday.For the past, use had to.
- Incorrect: Did you had to show your passport?
- Correct: Did you have to show your passport?After did, use have, not had.
Practise this rule
Related rules
Where this rule sits
All A2 rulesModal verbs: all rules