A Memorandum of Understanding (MOU), also called heads of terms or a letter of intent, records the intentions of two or more parties who are planning to work together, before they sign a full contract. The big question is whether it is legally binding, and the answer is "usually not, but be careful". Here is a plain-English guide for England and Wales.
What an MOU is for
An MOU sets out the shared understanding of a proposed deal or collaboration, the purpose, each party's role, the rough commercial terms and the timetable. It is typically used to:
- align expectations early and show intended commitment to a deal (though in England and Wales a bare obligation to negotiate or use best endeavours to agree terms is generally unenforceable for uncertainty; only specifically drafted binding clauses, such as confidentiality or exclusivity, will create enforceable obligations);
- give a framework for the detailed contract to follow;
- support funding, board approval or due diligence; and
- agree some points that the parties do want to be binding straight away (like confidentiality).
It is common in joint ventures, partnerships, M&A, and major commercial deals.
Is an MOU legally binding?
Usually not, on the main arrangement. An MOU normally records intentions, not enforceable obligations, and is generally marked "subject to contract" to make clear that no binding deal exists until a formal agreement is signed.
But certain clauses are often made binding, deliberately, typically:
- confidentiality;
- exclusivity (a promise to negotiate only with each other for a period);
- costs (each side bears its own); and
- governing law.
So a well-drafted MOU is usually part binding, part non-binding, and it should say clearly which is which. Ambiguity is the main risk.
A cautionary point: you can be bound by accident
Whether something is binding depends on substance, not the label. Even where parties think they are still "subject to contract", a court can find that a binding contract was formed by their conduct, for example if they started performing and treated the deal as done. (The Supreme Court made exactly this point in a well-known case where work proceeded despite a "subject to contract" understanding.) The lessons: be clear about what binds, and don't start performing as if a deal is concluded unless you intend to be bound. Also note that clarity alone is not always sufficient; for the main deal to be enforceable, the document must also contain sufficiently certain terms and meet the usual contractual requirements (including any statutory formalities, for example for land transactions).
When do you need one?
An MOU is worth using when:
- you want to record progress and momentum before the full contract is ready;
- you need confidentiality or exclusivity locked in now;
- the deal is complex and you want to agree the shape before spending on detailed drafting; or
- a third party (lender, board, investor) needs to see documented intent.
You don't need one for simple deals you can document in a single contract straight away.
Practical tips
- State clearly which clauses are binding and which are not ("subject to contract").
- Keep the binding parts (confidentiality, exclusivity, costs, governing law) tight and enforceable.
- Don't include so much detail that it looks like a complete contract (which a court might enforce).
- Move to the full agreement promptly, an MOU is a stepping stone, not a destination.
- Have a solicitor review it, especially the binding/non-binding split.
Key takeaways
- An MOU records the parties' intentions before a full contract, common in JVs, M&A and major deals.
- It is usually not binding on the main arrangement (mark it "subject to contract"), except clauses deliberately made binding (confidentiality, exclusivity, costs, governing law).
- You can still be bound by conduct despite "subject to contract", be clear and don't perform as if the deal is done unless you mean it.
- Use one to lock in confidentiality/exclusivity and document intent; then move to the full agreement.
Sources
- General contract law on intention to create legal relations and "subject to contract" (including case law that a contract can be formed by conduct despite a "subject to contract" understanding)
- Commercial practice on heads of terms / MOUs in England & Wales (binding vs non-binding clauses)
--- 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.