Have to and Must
The difference between have to (external obligation) and must (personal/strong obligation)
Have to: Obligation and Necessity
I have to do something means it is necessary to do it, I am obliged to do it.
- You can’t turn right here. You have to turn left.
- I have to wear glasses for reading.
- He has to work late tonight, so he can’t join the team dinner.
- Last week the server crashed and we had to restore the backup manually.
- I haven’t had to file a support ticket for ages.
Questions and Negatives with Have to
Use do / does / did in questions and negative sentences (present and past simple):
| Form | Example |
|---|---|
| Present question | What do I have to do to get a new badge? (not |
| Present negative | Karen doesn’t have to work Saturdays. (not |
| Past question | ”Did you have to wait long for the client?” “No, only ten minutes.” |
Have to with Other Verb Forms
You can say I’ll have to …, I’m going to have to …, I might have to …, I may have to …:
- They can’t repair my laptop, so I’ll have to get a new one. (or I’m going to have to get a new one.)
- We might have to change our plans for the product launch. (or We may have to change …)
Must: Personal Opinion and Recommendations
Must is similar to have to. You can use either when you give your own opinion about what is necessary, or when you recommend something:
- I haven’t spoken to the new hire for ages. I must phone her. / I have to phone her. (= I say this is necessary)
- Mark is a really helpful colleague. You must meet him. / You have to meet him. (= I recommend this)
Have to for Facts vs. Must for Rules
Use have to (not usually must) to say what someone is obliged to do as a fact, not as the speaker’s opinion:
- I have to work from 8:30 to 5:30 every day. (a fact about my schedule)
- Jane has to travel a lot for her work.
Use must in written rules and instructions:
- Applications for the position must be received by 18 May.
- Safety helmets must be worn on the construction site.
The Past: Had to
Use had to (not must) for the past:
- I went to the meeting yesterday, but I had to leave early. (not
I must leave early)
Mustn’t vs. Don’t Have to
Mustn’t and don’t have to are completely different.
| Meaning | Example | |
|---|---|---|
| mustn’t | Don’t do it. It is prohibited. | This report is confidential. You mustn’t share it with anyone. |
| mustn’t | I promised I’d be on time. I mustn’t be late. | |
| don’t have to | You don’t need to do it (but you can if you want). | You don’t have to attend the meeting. I can go alone. |
| don’t have to | I don’t have to be at the presentation, but I’m going anyway. |
Have Got to
You can use have got to instead of have to:
- I’ve got to finish this report tomorrow. = I have to finish this report tomorrow.
- When has Helen got to leave? = When does Helen have to leave?
Quick Self-Check
Robert can't come out with us this evening. He _____ work late.
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I couldn't get a taxi last night. I _____ walk home.
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The deadline is firm. All reports _____ be submitted by Friday.
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You _____ tell anyone about the merger. It's strictly confidential.
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Richard _____ wear a suit to work, but he usually does.
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