“Have to”, “need” and “must”

Knowledge of the basics of English grammar will help you to communicate clearly and confidently. Here, we review the use of “have to”, “need” and “must” in the context of education.

Although all three options — “have to”, “need” and “must” — are used to talk about necessity and obligation, there are some important differences in their usage and meaning.

1. Obligation with “have to”

In spoken English, we generally prefer “have to” when we talk about something that is necessary or obligatory:

You have to enrol by Friday.

We also use “have to” when we refer to obligations imposed by formal rules or regulations:

Each student has to complete three modules.

You can negate “have to” in the same way you would any verb. Use this structure to show that something is not necessary:

You don’t/didn’t have to complete a year in industry to pass the course.

You can use “have to” in all the various tenses and forms:

You would have to do the leadership module this year.

I had to take the exams last September.

2. Obligation with “need”

You can show that something is necessary or required with “need”. Generally, it is followed by “to” + infinitive:

We need to update the course.

If you wish to suggest that something needs to happen, but you are not able to say who should do it, you can use the structure “need” + “-ing” form of the verb:

Our online course really needs updating.

Or the passive infinitive:

Our online course really needs to be updated.

We can negate “need” to show that something is not necessary or

obligatory, but that you can do it if you wish. There are two possible forms. The first option is generally preferred in the UK and the US. The second option is more common in British English:

You don’t need to attend the online sessions.

You needn’t attend the online sessions.

We normally form questions with “do” or “did”. In more formal language, “need” can also be treated as a modal verb:

Do/did we need to register in advance?

Need we register in advance?

3. Obligation with “must”

We typically use “must” to express an obligation in formal written instructions, especially when we refer to legal requirements. As

“must” is a modal auxiliary, it has only one form. We cannot use it in other tenses:

All documents must be submitted by 1 July 2020.

To express an obligation in the past, use “have to” in a past tense: All documents had to be submitted by 31 January 2019.

In British English, we often use “must” to show that there is a personal element to the obligation: That course sounds interesting. I really must do it this year.