Are heads of agreement binding in Australia?

A heads of agreement is a written record of the key terms two parties have agreed in principle, usually signed before the full contract is drafted. Whether it is legally binding is not determined by its name, but by the intention the document discloses and how complete its terms are.

This article explains what makes a heads of agreement binding under Australian contract law, walks through a realistic business sale to show the concept in action, and sets out the misconceptions that most often lead small business owners into trouble.

What a heads of agreement is

A heads of agreement, also called a term sheet, memorandum of understanding, letter of intent, or heads of terms, is a short document that captures the main commercial points of a deal. It is common in business sales, investments, joint ventures, supply arrangements, and lease negotiations, where parties want to record what they have agreed before spending money on due diligence, valuations, and legal drafting.

Businesses reach for a heads of agreement at the point in a negotiation where everyone wants to lock in the broad shape of the deal before spending money on due diligence, advisers, and drafting. It gives the parties a shared record of what has been agreed, which reduces the risk of one side later claiming the negotiation covered something different. It can also be a condition for moving forward: a buyer will rarely spend thousands on due diligence on the strength of a handshake alone.

The label matters less than the content. Australian courts do not enforce a document because it is called a "contract", nor ignore one because it is called a "heads of agreement". What matters is whether the document, read as a whole, amounts to a legally enforceable agreement.

Intention to create legal relations

The first essential element of a binding heads of agreement is the parties' intention to be legally bound. In commercial dealings between businesses, the law generally assumes the parties intend their written agreements to be enforceable, so the question is usually whether the document shows an intention to be bound immediately or only once a formal contract is signed.

That intention is judged objectively. A court looks at what a reasonable person in the parties' position would understand from the document's language, not at what one party privately claims it meant. Words of commitment such as "will", "must" and "agrees" point towards an intention to be bound, while expressions like "intend", "propose" or "in principle" point the other way.

This is why the heading on the page is not a reliable guide. Two documents with identical names can have opposite legal effects because of what the body of each one says. A document headed "Heads of Agreement" that sets out a complete bargain in mandatory language may be fully enforceable, while a document headed "Contract" that leaves the price and scope to be negotiated may not be a contract at all.

Certainty and completeness of terms

The second essential element is certainty. A court will not enforce an agreement it cannot understand or complete. The parties, the subject matter, the price, and the essential obligations must be identified with enough clarity for the court to know what it is being asked to enforce.

This is where many heads of agreement fall short. A document that says the parties "will negotiate a supply arrangement on terms to be agreed" leaves the essential terms open, and a court cannot fill that gap for you. A document that sets out the buyer, the business being sold, the price, and the completion date is far more likely to be enforceable, because nothing essential is left outstanding.

The three categories from Masters v Cameron

The leading Australian authority on whether parties are bound before a formal contract is signed is Masters v Cameron [1954] HCA 72. The High Court there described three situations:

• Binding now: the parties have settled all the terms, intend to be bound immediately, and the formal contract will simply restate those terms in fuller form. The heads of agreement is enforceable from signing.
• Binding now, performance later: the parties have agreed all terms and intend to be bound, but make performance of one or more terms conditional on the formal contract being executed.
• Not binding yet: the parties intend no contract at all until the formal document is signed. Either side can walk away before then without breaching anything.

In Masters v Cameron itself, a signed agreement for the sale of a farm expressed to be "subject to the preparation of a formal contract of sale" fell into the third category, and a deposit paid under it had to be returned because no binding contract existed.

What pushes a heads of agreement towards binding

The same case law shows what pushes a document into the first two categories:

• Complete terms: If nothing important is left for the formal contract, the heads of agreement is more likely to be treated as the deal itself.
• Commitment language: "The buyer will pay $500,000 on completion" reads differently from "the parties hope to agree a price".
• Conduct after signing: Paying a deposit, delivering goods, or starting work under the document suggests the parties treated it as binding. In Waltons Stores (Interstate) Ltd v Maher [1988] HCA 7, the High Court held that a party could be prevented from denying an agreement existed where its conduct encouraged the other party to assume the deal would proceed and to act on that assumption to its detriment. Even a non-binding document can therefore create exposure through reliance.
• No saving language: The absence of any statement that the document is non-binding or subject to a formal contract counts in favour of enforceability.

When only part of the document binds

Many heads of agreement are deliberately drafted so that only some clauses are binding. This is common and commercially sensible: the parties want confidentiality, exclusivity, cost-sharing and governing law to take effect immediately, while the commercial terms remain "subject to contract".

That structure is legitimate, but it must be made explicit. A clause saying "this document is non-binding except for clauses 4, 5 and 6, which are binding" leaves little room for argument. A document that says nothing, and mixes binding-sounding obligations with a note that it is "just a summary", invites a dispute about what was intended.

One clause worth particular care is a promise to negotiate the formal contract in good faith. In United Group Rail Services Ltd v Rail Corporation NSW [2009] NSWCA 177, the Court of Appeal held that an obligation to undertake genuine and good faith negotiations can be sufficiently certain to be valid and enforceable. Whether such a clause binds you depends on how it is drafted, and it can create obligations while negotiations are still running.

Worked example: selling the family business

Maria owns a Melbourne catering business and has agreed in principle to sell it to a larger hospitality group. The parties sign a one-page heads of agreement. It names the parties, describes the business, sets the price at $750,000, and says the buyer "will pay a $50,000 deposit within 14 days". It also includes a confidentiality clause and a 60-day exclusivity period, and ends with "formal sale agreement to be prepared".

The buyer pays the deposit and spends two months on due diligence. The seller then receives a higher offer and wants to back out, arguing the heads of agreement was never meant to be binding.

A court would likely take a different view. The price, the parties, the subject matter and the deposit obligation are all settled, and the buyer has performed part of the deal by paying. The final sentence does not necessarily save the seller: under Masters v Cameron, if the parties intended to be bound now with the formal contract merely restating the terms, the heads of agreement is enforceable. The seller may be held to the sale, or at least liable for the buyer's wasted due diligence costs.

Had the document said "the parties intend no binding obligations until a formal sale agreement is executed, except for the confidentiality and exclusivity clauses", the seller's position would be much stronger. The difference is a few lines of drafting.

Common misconceptions

A few misconceptions recur when small business owners rely on a heads of agreement:

• "Subject to contract" automatically protects me: It is a strong signal, but not a magic phrase. The High Court said in Masters v Cameron that no formula such as "subject to contract" always and necessarily produces a non-binding result. If the rest of the document is complete and the parties behave as though the deal is done, a court may still find a binding agreement despite the words.
• A non-binding heads of agreement creates no risk at all: Even where no contract exists, a party that encourages another to rely on the deal proceeding can face claims based on that reliance. The estoppel principles in Waltons Stores mean the cost of a careless "in principle" document can be real money.
• Vague terms keep me flexible: Leaving the price or scope "to be agreed" does keep the document non-binding, but it also means you have no enforceable deal if the other side walks away. A heads of agreement that is too vague to bind is usually too vague to protect.

When a commercial lawyer helps

A commercial lawyer's job at this stage is to make sure the heads of agreement does exactly what you want and nothing more. That means identifying which clauses should bind immediately, drafting the non-binding language so it is consistent throughout, checking that the parties are correctly named (a common source of enforcement problems), and confirming who is authorised to sign and how the document must be executed.

A lawyer will also flag the obligations that survive even a failed deal, such as confidentiality, exclusivity and cost-sharing, and will tell you when a standalone non-disclosure agreement would be safer than folding confidentiality into the heads of agreement. For a high-value transaction, the cost of that review is small against the cost of litigating whether a deal exists at all.

The decision your heads of agreement forces you to make

Every heads of agreement forces a choice: which parts of this deal bind now, and which bind only when the formal contract is signed. If you do not make that choice deliberately, the document will make it for you, and a court may decide it differently from what either party intended.

Before you sign, you should be able to answer one question about your own document: if the other side walked away tomorrow, which clauses could you enforce against them, and which of your own obligations could they enforce against you? If you cannot answer it from the words on the page, the drafting has not done its job, and a lawyer's review is the cheapest way to find that out.