Must and Have to

Must vs Have To

Both express obligation but from different sources. 'Must' comes from the speaker's internal conviction or logical deduction. 'Have to' expresses an external obligation imposed by rules, laws, or circumstances. 'Must not' means prohibition; 'do not have to' means no obligation — they are opposites.

Formula

Must — internal obligation

You must review this contract carefully. (speaker insists)

Must — logical deduction

She must be the new director. (I'm certain)

Have to — external obligation

All visitors have to sign in at reception. (company rule)

Must not — prohibition

You must not share your login credentials. (forbidden)

Do not have to — no obligation

You don't have to attend if you are busy. (it is optional)

Had to — past obligation

They had to cancel the event due to the storm.

Example Sentences

Visitors must sign the register before entering the building.

You don't have to work this weekend — it is optional.

All financial documents must be audited annually.

She had to submit the revised report by noon.

Employees must not disclose client information to third parties.

Does he have to attend every weekly meeting?

The figures are consistent — this must be the correct version.

You don't have to apologise; it was not your fault.

All new hires must complete the induction programme.

I had to rework the entire proposal after the client feedback.

Common Mistakes

You don't must work this weekend.

You don't have to work this weekend.

'Don't must' does not exist. Use 'don't have to' for no obligation.

Must not = not necessary

Must not = forbidden; Don't have to = not necessary

These two forms are OPPOSITE in meaning — a common TOEIC trap.

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