What does exchange of contracts actually mean?

Why is nothing binding until exchange?

Section 2 of the Law of Property (Miscellaneous Provisions) Act 1989 requires a contract for the sale or other disposition of an interest in land to be made in writing, to incorporate all the terms the parties have expressly agreed, and to be signed by or on behalf of each party. The terms may be set out in the document itself or brought in by reference to another document, which is how the Standard Conditions of Sale get into a short contract form. Where contracts are exchanged, section 2(3) requires one of the two parts, though not necessarily the same one, to be signed by or on behalf of each party, which in practice means each side signs its own part (checked 20 September 2026). An accepted offer, a handshake, an email from the estate agent and even a signed contract sitting in a conveyancer's file do not satisfy that, because the two parts have not been brought together. Until they are, there is no contract, and either side may withdraw without liability. Auctions are the exception: section 2(5)(b) puts a contract made at a public auction outside the rule altogether, so at auction the contract is made when the hammer falls and the buyer is committed there and then. A reservation agreement under the modern method of auction is a different thing again, and is not itself a contract to buy the property.

That is why the memorandum of sale says "subject to contract", why gazumping and gazundering are legally possible however unwelcome, and why a buyer spends money on searches and surveys before having any certainty. It is also why the weeks before exchange matter: they are the only time a buyer can investigate and withdraw without cost. Our what happens if my buyer pulls out guide looks at the same period from the seller's side.

Exchange is the mechanism by which the two signed parts are brought together so that a binding contract comes into existence. In practice the buyer signs one copy and the seller signs an identical copy, each conveyancer holds their client's signed part, and the contract is formed when the parts are exchanged.

What has to be in place before exchange?

On the buyer's side: all enquiries answered satisfactorily, all searches returned and reported on, the mortgage offer issued and every condition in it satisfied or capable of being satisfied by completion, the deposit received in cleared funds in the conveyancer's client account, buildings insurance arranged to start on exchange, the contract signed, and a completion date agreed with everyone else in the chain. Where a gifted deposit is involved, the lender's requirements on the gift must be met too; our gifted deposits guide explains them.

On the seller's side: the contract signed, the transfer approved, any onward purchase ready to exchange on the same day, the redemption figure for the mortgage obtained so that the sale will clear it, and vacant possession or the tenancy position confirmed. A seller with a related purchase cannot safely exchange on the sale until the purchase is also ready, because exchanging on one without the other leaves them homeless or owning two houses.

Your conveyancer will not exchange without your express authority, given after you have read the report on title and understood the completion date, the deposit and the consequences. That report-and-authorise step is the moment you take on liability, and it should never be rushed to meet an agent's deadline. Nor will a conveyancer exchange with a client's deposit not yet in the account, because the deposit has to be paid on exchange.

What actually happens at the moment of exchange?

Exchange is almost always done by telephone between the two conveyancers, using one of the exchange formulae the Law Society publishes for the purpose. Formula A is for use where one conveyancer holds both signed parts, formula B where each holds their own client's part, and formula C is the chain formula. The Law Society states that the formulae may be used both by solicitors and by those licensed by an appropriate professional body to undertake conveyancing, so a licensed conveyancer practice can use them, and the printed contract has a box recording which formula was used. Each confirms that they hold a part of the contract signed by their client, that the parts are identical, and the completion date to be inserted. They agree the time, both note it on their file, and from that moment the contract exists. The signed parts are then sent to each other by post or electronically, but the contract is already binding.

In a chain, exchange happens along the chain in sequence on the same day, and formula C allows a conveyancer in the middle to release their part to the next link for a period so that the whole chain can exchange within a window. If one link cannot exchange, none does, which is why a chain can be ready for weeks and then exchange in an afternoon.

The deposit passes at exchange. Under condition 2.2.1 of the Standard Conditions of Sale, fifth edition 2018 revision, it is ten per cent of the price, and condition 2.2.6 makes the seller's conveyancer hold it as stakeholder, so it cannot be released to the seller until completion. The printed conditions contain one exception and only one: condition 2.2.5 lets the seller use it as the deposit on another property in England and Wales that the seller is buying for their own residence, held on the same terms. Holding a deposit as agent rather than as stakeholder is not something the Standard Conditions provide for at all; it takes a special condition negotiated into the particular contract. Where the deposit does go up the chain under condition 2.2.5 it leaves the stakeholder protection, and if a contract higher up the chain fails through that buyer's default it can be forfeited there. A reduced deposit, commonly five per cent where the buyer's mortgage is high, can be negotiated, but the buyer's liability if they fail to complete is usually still the full ten per cent.

Who is responsible for the property between exchange and completion?

Under condition 5.1.1 of the Standard Conditions of Sale, fifth edition 2018 revision, the property is at the buyer's risk from the date of the contract, and condition 3.2.1 makes the buyer accept it in the physical state it is in at that date. If the house burns down the day after exchange, the buyer must still complete and pay the full price. That is why the buyer's conveyancer will not exchange until buildings insurance is in place from the moment of exchange, and why a lender makes cover a condition of the mortgage. Some contracts vary this and leave risk with the seller, but the default should be assumed unless the contract says otherwise. A flat is different: in most blocks the landlord insures the building under the lease and the leaseholders pay through the service charge, so the buyer of a flat should check that policy is in place and note their interest rather than taking out separate buildings cover.

The seller remains in possession and must keep the property in the state it was in at exchange, allowing for fair wear and tear, and must not remove fixtures or the contents listed as included on the fittings and contents form. The buyer normally has no right to enter before completion except for the purposes the contract allows, such as measuring up, and moving in early under licence is possible but needs careful terms.

Between exchange and completion the buyer's conveyancer makes the pre-completion searches, the OS1 at HM Land Registry and the K16 bankruptcy search, requests the mortgage advance for the day before or the day of completion, prepares the completion statement and the transfer deed, and sends the seller's conveyancer the money on the completion date. The length of that gap is whatever completion date the two sides agreed and wrote into the contract, and nothing else decides it. Where a contract leaves the date out altogether, standard condition 6.1.1 of the Standard Conditions of Sale supplies twenty working days after the date of the contract, but a date is almost always inserted, so that fallback is rarely reached (checked 20 September 2026). The same condition adds the part that costs money: time is not of the essence unless a notice to complete has been served, so completing late does not end the contract by itself but does expose the late party to compensation at the contract rate. Nothing should be booked, and no notice given on a tenancy, until contracts are exchanged and the date is fixed.

What happens if someone pulls out after exchange?

If either party is not ready on the completion date, the other can serve a notice to complete, which under condition 6.8.2 makes time of the essence and gives ten working days to complete, excluding the day the notice is given. Condition 6.8.3 also requires a buyer who paid less than ten per cent to make the deposit up to the full ten per cent straight away. What then runs is not interest but compensation under condition 7.2, and it does not simply fall on the buyer: condition 7.2.1 makes it payable by whichever party's total period of default is the greater, so a buyer who is late but less late than the seller pays nothing. Condition 7.2.2 calculates it at the contract rate on the purchase price, less the deposit where the buyer is the paying party, and only for the period by which that party's default exceeds the other's. The contract rate is defined in condition 1.1.1(e) as the Law Society's interest rate in force, which the Law Society sets at four per cent above Barclays Bank base rate and publishes on its own site. If the buyer still fails to complete, the seller may rescind the contract, forfeit the deposit and resell, and claim damages for any further loss, including a lower price on resale and the costs of the failed transaction.

If the seller fails to complete, the buyer may rescind and recover the deposit with interest, or apply to the court for specific performance, an order compelling the seller to transfer the property, together with damages for the delay. Courts grant specific performance for land because each property is unique and money is not an adequate substitute. Neither outcome is common, precisely because the consequences are serious and both parties know it.

A buyer who has exchanged and then discovers something they wish they had known has very limited remedies. The seller's replies to enquiries and the property information form can found a claim in misrepresentation if they were untrue, but nothing else that was discoverable before exchange gives a right to withdraw. Our what searches are needed guide is, in effect, a list of the things to find out first.

Can exchange and completion happen on the same day?

Yes. Simultaneous exchange and completion is common for chain-free cash purchases, auction-style transactions and some transfers between connected parties, where nobody needs notice to move and there is no chain to align. Our buying a house at auction guide explains that auction contracts bind on the fall of the hammer, which is exchange by another route.

The disadvantage is that nothing is binding until the money has actually moved, so both sides are exposed to a last-minute withdrawal, and any delay in the bank transfer means the parties have to decide on the day whether to exchange anyway and complete later. Where removals are booked or a chain is involved, a gap of at least a week between exchange and completion is the safer course. Our buying service will advise on the right gap for your transaction and will not exchange until you have authorised it in writing.