"Subject to contract": what it means and how to use it

What the phrase does

"Subject to contract" tells the other side that your exchanges are part of an ongoing negotiation, not an offer or an acceptance. It builds a condition into the discussion: no binding contract exists until that condition - usually the signing of formal documentation - is met.

It is the cleanest answer to the risk that runs through digital contracting, where an email or a messaging-app exchange is later treated as a concluded deal. The label keeps the whole conversation provisional until you decide otherwise.

Why English courts give it effect

While communications are marked subject to contract, courts read them as continuing negotiations rather than commitments, so the usual offer-and-acceptance analysis does not bite in the same way.

The result is that you can explore terms, exchange drafts and float numbers without each step hardening into an obligation. The protection lasts until the agreed formal step - typically signature of the contract - actually happens.

How to use it correctly

Put it where it will be seen. In email that means the subject line and the opening. A subject line can flag that the discussion is subject to contract, and an opening line can state that the email and the discussions remain subject to contract until a formal agreement is executed by authorised signatories.

Carry it into messaging too. If terms come up on a messaging app, open by noting that everything is subject to contract and that a formal proposal will follow. The wording costs nothing and changes how the whole exchange is read.

Keep the wording plain. Something as simple as opening with "this proposal is subject to contract" and adding that no binding agreement arises until both parties sign does the job - you do not need elaborate drafting for the label to take effect.

Subject to contract and without prejudice

In settlement discussions the phrase is often paired with "without prejudice". They do different jobs: subject to contract keeps the deal non-binding until signature, while without prejudice goes to whether the exchange can later be put before a court.

Using both can be appropriate in the right setting, but they are not interchangeable, and the exact wording for a given negotiation is worth confirming with counsel rather than copying by rote.

Be consistent across the whole thread

Protection depends on the impression the exchange gives as a whole. A single stray confirmation - an unguarded "agreed, then" - can undercut a thread you thought was safe.

Treat the wording as a standing condition, not a one-off label. Repeat it where the conversation moves channel, and make sure everyone on your side uses it the same way, so the protection is not lost by one person's casual message.

When the protection fails: waiver by conduct

The shield can be waived by conduct. If both sides start performing as though the deal is live - delivering goods, making payments, beginning the work - a court may conclude they agreed to proceed without waiting for the formal document.

That is the lesson of RTS Flexible Systems Ltd v Molkerei Alois Müller GmbH & Co KG [2010] UKSC 14, where the Supreme Court accepted that parties can waive a subject-to-contract understanding through how they behave. Once performance is under way, the wording you relied on may no longer save you.

How the protection is lost in practice

The usual loss is not a formal waiver but drift. One side starts work to hit a deadline, the other accepts the early delivery, invoices are raised and paid, and the formal signature never quite happens - yet both have behaved as though a contract already exists.

That momentum is what a court reads. If your team keeps performing while the lawyers are still drafting, the conduct can be treated as the parties choosing to be bound, just as in RTS. Protective wording does not travel with you once your actions contradict it, so the discipline is to hold the line on performance until you have decided to commit.

Turning the protection off on purpose

Because conduct can erode the protection by accident, the safer practice is to end it deliberately rather than drift out of it. When you are ready to commit, say so: remove the subject-to-contract wording, confirm the essential terms, and state clearly that the communication is your formal acceptance.

Then follow up with the formal contract within the agreed timeline. The discipline is symmetry - be as clear about when you start being bound as you were about not being bound yet, so neither side is guessing.

What it means for review

Whether a draft preserves or quietly drops conditionality often hides in small wording changes to acceptance, conditions precedent and variation clauses. A deleted "subject to" or a reworded condition can change when the parties become committed.

Reading those edits carefully is how you keep "we are still negotiating" from turning into "we have already agreed" without anyone on your side actually deciding to commit.

It is also worth checking that preliminary documents - heads of terms, a letter of intent, a purchase order - are not drafted as though they already bind. Those are exactly the places where conditionality is quietly won or lost.