One Minute Grammar

Modals of Obligation

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Modals of Obligation

The words “have to,” “need to,” and “must” show an obligation.

In spoken English, speakers usually say “have to” and not “must.”

• We have to go.
• You have to try harder!

In written language, writers usually use “must.”

• We must finish this by Friday.
• All employees must wear a uniform.

The modal “need to” is appropriate for both, but is used less than “have to” and “must.”

• We need to pay this bill
• All employees need to wear a helmet

‘Do not have to” and “do not need to” have different meanings than “must not.”

One form means not necessary

• I don’t have to work today.
• We don’t need to pay this.

The other form means not allowed.

• You must not say that.
• We mustn’t make any mistakes.