Have to / Must / Don't Have to

1. Simple explanation

Have to and must both say that something is necessary — an obligation is something you need to do, not something you choose. Use have to for rules that come from outside (a boss, a law, a school): 'I have to wear a uniform.' Use must for your own strong feeling: 'I must call my mother.' Careful: don't have to means 'it is not necessary — your choice,' but mustn't means 'forbidden — do not do it!'

2. Detailed explanation

Start from zero. Sometimes we act because we want to (I want to watch TV); sometimes because we need to — somebody or something makes it necessary. That idea — 'it is necessary, I have no real choice' — is called an obligation. This lesson teaches the two English word-groups for obligation: have to and must. Both mean 'it is necessary.' The difference is where the necessity comes from: have to for necessity from outside you — a law, a boss, a school rule, or a situation. Use must when the necessity comes from inside you: your own strong feeling. 'I have to wear a uniform' (my job's rule). 'I must call my mother tonight' (my own decision).

Now the forms, step by step. Have to changes with the person: I/you/we/they have to, but he/she/it has to — 'She has to leave at six.' After have to and must, use the plain verb with no changes and no extra 'to': 'She has to go,' never 'She has to goes' or 'She must to go.' Questions and negatives with have to use do/does: 'Do you have to work today?' 'He doesn't have to work on Sundays.' Must has no do/does forms and never changes: the question 'Must I go?' sounds old-fashioned; real speakers ask 'Do I have to go?'

Let's take three sentences apart, word by word. 'I have to wear a uniform at work': I (me) + have to (it is necessary for me) + wear (put on my body) + a uniform (special clothes for a job) + at work (at my job). 'She has to leave at six': She (a woman) + has to (it is necessary for her — has because she is one person) + leave (go away) + at six (at 6 o'clock). 'You must try this cake!': You + must (my strong recommendation) + try (taste it) + this cake. And here is the most important contrast in the lesson: 'You don't have to come' means coming is NOT necessary — you are free to choose. 'You mustn't come' means coming is FORBIDDEN — do not come! Don't have to removes a duty; mustn't creates a ban.

For the past, both use one form: had to — 'Yesterday I had to stay late.' No 'musted' exists. Americans often say 'gotta' for have to — 'I gotta go' — but learn the full form first, and never write 'gotta' formally. Short answers use do: 'Do you have to pay?' — 'Yes, I do.' / 'No, I don't.'

3. Formula / structure

Step by step — how to build a sentence:

negative — forbidden:

negative — not necessary:

past:

positive — have to:

positive — must:

question:

4. When to use it

• Outside rules and laws (have to): 'Drivers have to stop at red lights.'
• Jobs and school duties (have to): 'Nurses have to wash their hands.'
• The speaker's strong feelings (must): 'I must call my mom today.'
• Strong recommendations (must): 'You must visit the Grand Canyon!'
• Official signs and notices (must): 'Visitors must register at the desk.'
• Saying something is NOT necessary (don't have to): 'You don't have to pay — it's free.'
• Saying something is forbidden (mustn't): 'You mustn't smoke in the hospital.'
• Past obligations (had to): 'We had to wait for two hours.'

5. When NOT to use it

• Don't use mustn't when you mean 'not necessary': ✗ 'You mustn't come if you're busy' (this FORBIDS coming!) → ✓ 'You don't have to come if you're busy.'
• Don't put 'to' after must: ✗ 'must to go' → ✓ 'must go.'
• Don't change the verb after have to: ✗ 'She has to goes' → ✓ 'She has to go.'
• Don't use must for the past: ✗ 'Yesterday I must work' → ✓ 'Yesterday I had to work.'
• Don't answer with 'Yes, I have': ✗ 'Do you have to leave?' — 'Yes, I have' → ✓ 'Yes, I do.'

6. Positive examples

• I have to get up at 6 a.m. every day.
• She has to wear a seat belt in the car.
• Students have to do their homework.
• We have to show our passports at the airport.
• You must see this movie — it's wonderful!
• He has to take his medicine twice a day.
• Drivers have to stop at a red light.
• I must remember to call grandma tonight.
• They have to finish the project by Friday.
• My sister has to practice piano every day.
• You must try the soup — I made it myself!

7. Negative examples

• You don't have to pay — it's free.
• He doesn't have to work on Sundays.
• We don't have to wear uniforms at this school.
• She doesn't have to cook tonight.
• You mustn't park here.
• Students mustn't use phones during the test.

8. Questions

• Do you have to work tomorrow?
• Does he have to pay for the course?
• Do we have to bring anything?
• Why do you have to leave so early?
• Did you have to wait long yesterday?
• Do I have to sign this form?

9. Short answers

• Yes, I do. / No, I don't.
• Yes, she does. / No, she doesn't.
• Yes, we do. / No, we don't.
• Yes, they do. / No, they don't.
• Yes, he does. / No, he doesn't.

10. Common mistakes

11. American English notes

12. Similar grammar — comparison

13. Natural spoken English

• 'I gotta go — my train leaves in ten minutes!'
• 'Do you have to work late again?' — 'Yeah, I do.'
• 'You don't have to wait for me.'
• 'You gotta try this burger. Seriously.'
• 'He has to be at the airport by five.'
• 'You mustn't tell Jake — it's a surprise!'

14. Real-life examples

• Road sign: 'All drivers must stop.' / 'You mustn't park here — tow zone.'
• At school: 'Students have to wear their ID cards.'
• At the airport: 'Passengers have to show a boarding pass.'
• At work: 'I have to clock in at 9.' / 'We don't have to dress up on Fridays.'
• At the doctor: 'You have to take this twice a day. You mustn't skip a dose.'
• At home: 'You don't have to wash the dishes — the dishwasher will do it.'

15. Mini dialogue

16. Summary

17. Practice exercises

Warm up with the first questions, then take the full quiz — every answer has a detailed explanation (parts 19–20 of this lesson: answer key + explanations live inside the quiz feedback).

18. The full quiz

50 questions, mixed formats, in difficulty order: easy → medium → intermediate → challenging → advanced.

Mark lesson completed