Contracts are the backbone of business, but a binding contract does not need to be a long document, or even in writing. Under the law of England and Wales, a contract is legally binding when a set of key elements are present. Here is a plain-English guide to what they are.
The core elements
For a valid, legally binding contract, you generally need all of the following:
1. Offer
A clear offer, a definite proposal to be bound on specific terms (for example, "I will sell you 100 units at £5 each"). An offer must be distinguished from an "invitation to treat" (such as goods on a shop shelf or an advert), which merely invites others to make offers.
2. Acceptance
An unqualified acceptance of the offer on its terms. If the response changes the terms, it is a counter-offer, not an acceptance (which the original offeror can then accept or reject). Acceptance must generally be communicated to the offeror.
3. Intention to create legal relations
The parties must intend the agreement to be legally binding. In commercial dealings this is presumed; in social or domestic arrangements it is presumed not to exist (though either presumption can be rebutted by evidence).
4. Consideration
Each side must give something of value (consideration) in exchange for the other's promise (money, goods, services, or a promise to do/not do something). Consideration must be sufficient but need not be adequate (it does not have to be a fair price). The main exception is a contract made as a deed, which is binding without consideration.
5. Capacity
The parties must have the legal capacity to contract. Certain people have limited capacity (for example minors (under 18) and those who lack mental capacity) and some contracts with them may be unenforceable or voidable.
6. Certainty of terms
The agreement must be sufficiently certain and complete, the essential terms must be clear enough for a court to enforce them. An "agreement to agree" key terms later may be too uncertain to bind.
Two more points: legality and form
- Legality. A contract to do something illegal or contrary to public policy is not enforceable.
- Form. Most contracts can be oral or written. But some must be in a particular form, for example, contracts for the sale or other disposition of an interest in land must be in writing, contain all the expressly agreed terms, and be signed by or on behalf of each party (Law of Property (Miscellaneous Provisions) Act 1989); guarantees must be evidenced in writing and signed by the guarantor (or an authorised signatory) to be enforceable; and certain contracts must be made by deed.
Why it matters in practice
Because a contract can be formed orally or even by conduct, businesses sometimes become bound without realising it, or argue about what was agreed. To protect yourself:
- put important agreements in writing with clear terms;
- make sure your terms and conditions are incorporated before the deal is done;
- be careful with words like "subject to contract", which signal you are not yet bound.
Key takeaways
- A valid contract generally needs: offer, acceptance, intention to create legal relations, consideration, capacity, and certainty of terms.
- Consideration must be sufficient but need not be adequate, unless the contract is a deed, which needs none.
- Watch legality and any special form requirements (e.g. writing for land contracts).
- Contracts can be oral or by conduct, so use clear written terms and "subject to contract" where you are not yet committing.
Sources
- General law of contract in England & Wales (offer, acceptance, consideration, intention, capacity, certainty)
- Law of Property (Miscellaneous Provisions) Act 1989 (contracts for the sale of land must be in writing)
- Rules on contracts made by deed (binding without consideration) and form requirements for guarantees
--- This article is general information about the law of England & Wales as at 2026, not legal advice. For advice on your circumstances, consult a qualified solicitor.