Shall, Will and Must in Contracts: A Language Guide4 min read

Open almost any English contract and you will meet the word “shall” within a few lines: “The Supplier shall deliver the Goods…” For learners it is a puzzle. Your textbook said “shall” is for offers (“Shall I open the window?”) and is old-fashioned for the future. So what is it doing here?

A quick note before we start. This post is about the language only. It is not legal advice, and it does not tell you how any particular clause would be read in any particular country. For that you need a qualified lawyer. Drafting habits also vary between organisations and legal systems, so treat what follows as a guide to reading and writing, not as a rule book.

Shall: the traditional word for a duty

In traditional contract English, “shall” is used to say that a party has to do something.

The Tenant shall pay the rent on the first day of each month.

It reads as “has a duty to”. The negative, “shall not”, works the same way for prohibitions.

The Contractor shall not sub-contract any part of the Works without written consent.

You will also see “shall” in statements that describe how something works, such as “This Agreement shall be governed by the laws of…” It is simply the standard formal register for that kind of sentence.

Must: the plain English alternative

Some modern contracts, and many plain-English drafting guides, prefer “must” for obligations.

The Tenant must pay the rent on the first day of each month.

The idea is that “must” means “is required to” for every English speaker, whereas “shall” is easy to misuse. Some writers use “shall” for requirements, predictions and intentions all in the same document, which makes the meaning less certain. “Must” avoids that problem. Both styles exist today, and you should recognise both.

Will: be careful

In everyday English, “will” is the ordinary future: “The goods will arrive on Monday.” In a contract, “will” can mean a prediction, a promise or an intention, depending on how the document is written. Some contracts use “will” for obligations in a more informal style. Others keep “will” for facts about the future and use “shall” or “must” for duties. If you are writing, choose one approach and stay consistent. If you are reading, look at how the document uses the words in its own definitions or interpretation clause, if it has one.

May and may not

“May” usually gives permission.

The Buyer may terminate this Agreement by giving thirty days’ notice.

It means the Buyer is allowed to, but does not have to. “May not” can be ambiguous (does it mean “is not allowed to” or “might not”?), so many drafters prefer “must not” or “shall not” for prohibitions.

Should: usually too weak

“Should” expresses advice or expectation: “Notices should be sent to the following address.” In general writing that is fine. In a contract, if you intend a firm requirement, “should” leaves doubt about whether it is really required. If you see it in a contract you are reading, it is worth paying attention to how strong the sentence is meant to be.

Comparing them side by side

• shall / must: a duty. “The Seller shall (must) provide a warranty.”
• shall not / must not: a prohibition. “The Seller shall not (must not) assign the contract.”
• may: permission. “The Buyer may inspect the goods.”
• will: usually a future fact, sometimes a promise depending on the document. “The invoice will be issued monthly.”
• should: a recommendation or weaker expectation.

A small exercise

Read each sentence and decide: duty, permission or prohibition?

1. The Company shall keep accurate records.
2. The Employee may work from home on Fridays.
3. The Licensee must not copy the software.

Answers: 1 duty, 2 permission, 3 prohibition. If you got those right, you have the basic map. The details and edge cases are where a lawyer’s judgement matters.

Reading with confidence

You don’t have to memorise every nuance to read contract English better. Learn the five verbs above, notice them as you read, and underline them in different colours: duties in one colour, permissions in another, prohibitions in a third. After a few contracts, the pattern becomes automatic.

For more on this kind of language, the free Legal English chapter on contract law gives you reading and vocabulary practice, and the English for Lawyers page explains the wider course. If you would like to talk about a bespoke programme for your own practice area, you can write to info@abcenglishonline.com.