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. Pro tip: from me = must; from outside = have to; past = had to.
✏️ 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. Correct this: '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.
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).
⬇︎ Download the Lesson Pack (PDF)
Printable worksheet + answer key + one-page summary. Free to use and print in class with attribution. Join the newsletter for new packs and cheat sheets.