The Moment a Deal Becomes a Contract

Treat the sections below as a sequence. With the point at which negotiation turns into obligation, getting the early decisions right makes the later ones much easier.

An offer and an invitation to deal

A shop window displaying a price is generally treated as an invitation to make an offer rather than an offer itself. The reasoning is practical, since a seller with limited stock cannot be bound to everyone who reads the sign.

An offer is a statement made with the intention that saying yes to it is enough to create obligations. Advertisements, catalogues and tender documents usually sit on the invitation side of that line for the same practical reason. Where a statement genuinely promises something to anyone who performs a stated act, courts have been willing to treat it as a real offer.

Acceptance has to match

Acceptance in its classic form must correspond to the offer without adding, removing or adjusting anything material. A reply that changes the delivery date or the payment terms is normally treated as a counter-offer rather than agreement. A counter-offer usually kills the original offer, so the first proposal cannot simply be revived by changing your mind afterwards.

This is why long email chains can end with neither side certain which version of the terms is on the table. Commercial practice deals with the problem by restating the whole agreed position rather than trading amendments piecemeal.

Communication and the gap in the post

An acceptance generally has to reach the other side, because a decision kept in your own head changes nothing. Legal systems have wrestled for a long time with what happens when a message is sent but not yet received. Different rules apply to instant communication and to messages that travel, and the detail varies between jurisdictions.

Modern contracts often solve the problem directly by stating when a notice is deemed to have been received. That clause looks like padding until a deadline turns on whether an email arrived before or after midnight.

Did anyone intend to be bound

Beyond offer and acceptance, most systems ask whether the parties intended their arrangement to have legal consequences. Social and domestic arrangements are often presumed not to, on the sensible view that dinner plans are not contracts.

Commercial dealings usually carry the opposite presumption, since businesses are taken to mean what they write down. Presumptions can be displaced by evidence, which is why the surrounding correspondence matters as much as the document.

Language such as binding in honour only exists specifically to rebut the commercial presumption where the parties want that.

The brakes people put on negotiation

Phrases marking a document as subject to contract are used to signal that nothing is agreed until a formal document is signed. Heads of terms and letters of intent try to record progress without creating obligations, which is harder than it sounds. Courts look at substance rather than labels, so a document that behaves like a contract may be treated as one.

Read strictly, mixed documents that bind on confidentiality but not on price are common and generally effective when drafted carefully. The safest habit is to say plainly, in the document, which parts are meant to bite and which are not.

Where housing, employment, money or family arrangements are genuinely at stake, the next step is a solicitor or an advocate, not an article.

Why the moment matters

Once a contract exists, walking away stops being a change of mind and becomes a breach with consequences attached. Risk in goods, insurance obligations and the start of time limits are all often pinned to the formation date. Where two sets of standard terms have been exchanged, working out which set governs can decide an entire dispute.

Reconstructing the moment months later is the kind of task that turns on emails nobody thought worth keeping. Keeping a clean record of what was sent and when is unglamorous and repeatedly decisive.

The takeaway

Know which side of the line a conversation is on, and say so out loud. This article explains general principles and is not legal advice.

Get it in writing, keep it dated, and file it where you will find it again.