had to / didn't have to (past obligation)

Rules

• Rule 1: Positive → had to + base verb

  had to is the same for all subjects (I, you, he, she, we, they). The base form of the verb comes after it.

  Pattern: subject + had to + base verb

  Example: She had to stay at home because of the storm.

  Example: We had to run to catch the bus.

• Rule 2: Negative → didn't have to

  didn't have to = it wasn't necessary. didn't shows the past, so have stays in the base form. Careful: mustn't means “not allowed”. For “it wasn't necessary”, use didn't have to.

  Pattern: subject + didn't have to + base verb

  Example: We didn't have to do homework on the holiday.

  Example: He didn't have to pay. It was free.

• Rule 3: Questions → Did … have to?

  Make questions with Did; have to stays in the base form. Short answers: Yes, I did. / No, I didn't. With question words: What / Why / How long did you have to…?

  Pattern: Did + subject + have to + base verb?

  Example: Did you have to walk home? — Yes, I did.

  Example: Did they have to wait? — No, they didn't.

Common mistakes

• Yesterday I must study. → Yesterday I had to study.

  must has no past form → had to.

• We didn't had to wait. → We didn't have to wait.

  After didn't, use have.

• She had to went home. → She had to go home.

  Base verb after had to.