We use the verb need to talk about things that we must do. We use to + infinitive (e.g. to work, to go) after need:

After he/she/it we use needs:

• Mary / She needs to buy some chicken for dinner.

We make negatives, questions, and short answers with a form of do:

• You don’t need to wear a suit at work.
• She doesn’t need to buy any bread.
• Do you need to go to the doctor’s? ∼ Yes, I do. / No, I don’t.
• Does Joan need to buy any bread? ∼ Yes, she does. / No, she doesn’t.

We can also use need to talk about things we must get. Here we use an object after need:

To talk about what we do not need to do, we can use needn’t. We use an infinitive (e.g. work, go, eat) after needn’t. Needn’t has the same meaning as don’t/doesn’t need to:

• You needn’t go to the shops. We have enough bread. (or You don’t have to go …)
• Paul needn’t go to work tomorrow. (or Paul doesn’t have to go …)

We cannot use needn’t before an object (e.g. your hat and gloves). We must use don’t need:

You don’t need your hat and gloves – it’s quite warm outside. (not You needn’t your …)

We can use needed to for past time:

• I needed to get up early yesterday because I had to go to the airport.

Notice the meaning of needn’t have done:

• I needn’t have worn my hat and gloves – it was a warm day. (= I wore my hat and gloves but they weren’t necessary because the weather was warm.)
• You needn’t have bought any bread – we have plenty. (= You bought some bread, but it was not necessary.)