GV

Must vs Have to

Expressing obligation and necessity with must / have to / don't have to / mustn't

intermediate

When to Use Must vs Have to

  • •Personal/strong obligation: You must wear a helmet.
  • •External rules/requirements: We have to submit the form by Friday.
  • •Prohibition: You mustn't park here.
  • •No necessity: You don't have to come early.
  • •Logical deduction (must): She must be at home (I'm almost sure).

How to Form Must vs Have to

Affirmative (+)

Must + base verb; Have to + base verb

Negative (-)

Must not (mustn't) + base verb; Do/does not have to + base verb

Question (?)

Must + subject + base verb? / Do you have to + base verb?

💡 Mustn't = prohibition. Don't have to = not necessary. Past: had to. Use must for deductions (strong belief).

Examples of Must vs Have to

✓You must finish this today.

✗You must to finish this today.

No 'to' after must.

✓We have to wear badges.

✗We must to wear badges (external rule).

Have to fits external obligation; no 'to' after must.

✓You don't have to call.

✗You mustn't call if you don't need.

Don't have to = not necessary; mustn't = prohibition.

✓She must be at home.

✗She has to be at home (deduction).

Use must for strong logical deduction.

Common Mistakes with Must vs Have to

💡 Practice Tips for Must vs Have to

  • • Must = personal/strong obligation or deduction; have to = external rules/obligation.
  • • Mustn't = prohibition (strong no). Don't have to = optional/not required.
  • • In past, use had to for obligation; use must have + V3 for past deduction.
  • • No 'to' after must/mustn't; include 'to' after have/has to.
Quick Quiz
  1. 1.You   smoke here — it's strictly forbidden.
  2. 2.The party is casual — you   wear a tie.
  3. 3.All employees   wear ID badges in the building.
  4. Question 4: I really blank (finish) this report tonight — I promised my boss.
    4.I really (finish) this report tonight — I promised my boss.
  5. Question 5: Last week we blank (work) on Saturday because of the deadline.
    5.Last week we (work) on Saturday because of the deadline.
  6. Question 6: You blank (not tell) anyone about this. It's a secret.
    6.You (not tell) anyone about this. It's a secret.
  7. Question 7: blank I ___ (submit) this form today, or can it wait?
    7. I ___ (submit) this form today, or can it wait?
  8. Question 8: Look at the sky — it blank (be) about to rain. (deduction)
    8.Look at the sky — it (be) about to rain. (deduction)
  9. Question 9: Children under five blank (not pay) for the museum.
    9.Children under five (not pay) for the museum.
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