Grammar › Modal Verbs › Must vs Have to
Must vs Have to
'Must' and 'have to' both mean obligation. Choose by where the obligation comes from:
- Must — from the speaker: a personal need or a rule you're stating (You must be quiet).
- Have to — from outside: laws, rules, jobs, circumstances (I have to work late).
For the past, always use 'had to'. And remember: 'mustn't' = forbidden, 'don't have to' = not necessary.
The difference in one table
| Must | Have to | |
|---|---|---|
| Obligation from | the speaker (feeling / stated rule) | outside (law, job, others) |
| Past form | — (use had to) | had to |
| Negative | mustn’t = forbidden | don’t have to = not necessary |
| Example | I must call the doctor. | I have to wear a uniform. |
Use must when the push comes from you; use have to when it comes from the world around you.
When to use each
Must — the speaker’s own obligation
- I must stop eating so late. (I feel it)
- You must show your badge. (a rule I’m stating)
Have to — outside obligation
- We have to file taxes by April. (the law)
- He has to travel a lot for work. (his job)
⚠️ The negatives are opposites: You mustn’t tell her (don’t — it’s a secret) vs You don’t have to tell her (you can if you want, but it’s not required).
Common mistakes
1. Using ‘must’ for the past. I must work late yesterday → I had to work late yesterday.
2. Swapping the negatives. You mustn’t come if you’re busy (meaning it’s optional) → You don’t have to come if you’re busy.
3. Adding ‘to’ after ‘must’. You must to sign here → You must sign here.
✏️ Practice: Must vs Have to
1. I keep oversleeping. I really ___ buy a louder alarm.
2. At my company, we ___ clock in by nine.
3. Yesterday the car broke down, so I ___ take the bus.
4. It's a secret. You ___ tell anyone.
5. It's a casual party — you ___ dress up.
6. She ___ wear glasses for driving; it's on her licence.
7. Which comes from an OUTSIDE rule?
8. Choose the correct version of: 'Last week I must finish two reports.'
9. Passengers ___ fasten their seatbelts during take-off.
10. The ticket is already paid, so you ___ bring any money.
11. Fill in the gap
I really ___ exercise more. It's my own decision.
Type one word.
12. Correct the mistake
I must work late yesterday.
Type the whole corrected sentence.
13. Fill in the gap
You ___ come if you're busy. It's optional.
Type three words.
Frequently asked questions
What's the core difference between 'must' and 'have to'?
'Must' usually comes from the speaker (a personal feeling or a rule they state); 'have to' comes from outside — a law, job or other people.
Which one for the past?
Only 'had to'. 'Must' has no past form for obligation: Yesterday I had to work.
Are the negatives the same?
No. 'Mustn't' means forbidden (You mustn't park here). 'Don't have to' means not necessary (You don't have to park here).
👩🏫 For teachers
CEFR objectives for “Must vs Have to”:
- Can choose between 'must' and 'have to' by source of obligation (CEFR B1).
- Can use 'had to' as the only past form.
- Can contrast 'mustn't' (prohibition) and 'don't have to' (no necessity).
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