Exchange of Contracts Explained for Sellers
What actually happens when contracts are exchanged, what becomes legally binding, and your obligations as a seller in England and Wales.
What you need to know
Exchange of contracts is the moment a property sale becomes legally binding in England and Wales. The buyer\u2019s and seller\u2019s solicitors exchange signed contracts by telephone, the buyer pays the deposit (typically 10%), and a completion date is fixed. After exchange, neither party can withdraw without facing significant financial penalties.
- Exchange of contracts is the point at which your sale becomes legally binding — before exchange, either party can walk away without penalty.
- The buyer pays a deposit (usually 10% of the purchase price) on exchange, which you are entitled to keep if they default.
- Solicitors exchange contracts by telephone using one of the Law Society’s agreed formulas — the process itself takes only minutes.
- After exchange, you are legally obligated to sell the property on the agreed terms and vacate by the completion date.
- Buildings insurance responsibility technically passes to the buyer on exchange, but you should maintain your cover until completion.
Pine handles the legal prep so you don't have to.
Check your sale readinessExchange of contracts is the single most important milestone in any property sale. It is the moment when a sale that could previously have collapsed at any time becomes a binding legal commitment. For sellers, understanding exactly what happens at exchange, what obligations it creates, and what protections it provides is essential to navigating the process with confidence.
This guide explains the mechanics of exchange from the seller's perspective, covering how the process works, what your solicitor does, what becomes legally binding, and what you need to do before and after exchange day. It applies to residential property sales in England and Wales under the Law Society's Standard Conditions of Sale (6th Edition).
If you want to understand the full timeline leading up to this point, see our guide on how long exchange of contracts takes.
What is exchange of contracts?
In England and Wales, a property sale is not legally binding until contracts are exchanged. Before that point, either the buyer or the seller can withdraw without legal penalty — which is why around 30% of agreed sales fall through before exchange, according to Propertymark.
Exchange of contracts is the formal process by which the buyer and seller become legally committed to the transaction. Identical contracts, one signed by the buyer and one signed by the seller, are “exchanged” between the two solicitors. Once exchange is confirmed, neither party can back out without facing serious financial and legal consequences.
The exchange also fixes the completion date — the day on which the buyer pays the remaining purchase price, you hand over the keys, and ownership of the property formally transfers. To understand what happens on that day, see our guide on what happens on completion day for the seller.
How exchange of contracts works: step by step
The exchange process follows a well-established procedure. Here is what happens from the seller's perspective.
1. Signing the contract
Before exchange can take place, your solicitor sends you the final version of the contract for your signature. This will have been through several rounds of negotiation between the two solicitors, with terms such as the completion date, what fixtures and fittings are included, and any special conditions all agreed.
You sign the contract and return it to your solicitor. This does not commit you to the sale — it simply means your solicitor holds a signed contract ready for when both sides are prepared to exchange. The buyer goes through the same process on their side.
2. The deposit
The buyer must have their deposit funds available before exchange can proceed. The standard deposit is 10% of the purchase price, though a reduced deposit of 5% is sometimes negotiated. In a chain, the deposit from the buyer at the bottom is often passed up through the chain using the deposit from one transaction to fund the next.
The deposit is held by your solicitor as stakeholder until completion, meaning they cannot release it to you until the sale completes. This protects the buyer in case something goes wrong after exchange. If the buyer defaults, you become entitled to keep the deposit.
3. The exchange telephone call
Exchange itself happens by telephone between the two solicitors. They use one of the Law Society's agreed exchange formulas, most commonly Formula B (used in chains) or Formula C (used for more complex chains). During the call, the solicitors confirm the details of the contracts, the deposit amount, and the agreed completion date.
The telephone call typically takes just a few minutes. Once both solicitors confirm that exchange has taken place, it is legally binding. Your solicitor will then call you to confirm that contracts have been exchanged and tell you the agreed completion date.
4. After the call
Following the telephone exchange, the solicitors physically post or deliver the signed contracts to each other so that each solicitor ends up holding the contract signed by the other party. This is a formality — the exchange is already legally binding from the moment it is confirmed on the telephone.
What becomes legally binding at exchange
Exchange creates a binding contract between you and the buyer. The key terms that become enforceable are set out below.
| Term | What it means for you as the seller |
|---|---|
| Sale price | You are committed to selling at the agreed price. The buyer cannot renegotiate downward (gazunder) and you cannot accept a higher offer from another buyer. |
| Completion date | You must be ready to give vacant possession on this date. If you fail to complete on time, you could be liable for penalty interest and damages. |
| Vacant possession | You must hand over the property empty of all personal belongings and occupiers by completion, unless specific items are listed as included in the contract. |
| Property condition | You must maintain the property in substantially the same condition as at exchange. Any significant deterioration (beyond fair wear and tear) could entitle the buyer to claim compensation or, in extreme cases, refuse to complete. |
| Fixtures and fittings | Everything listed as included on the TA10 Fittings and Contents Form must be left in the property. Anything listed as excluded can be removed. |
| Special conditions | Any conditions negotiated into the contract — such as carrying out specific repairs, indemnity insurance arrangements, or management pack obligations for leasehold properties — become enforceable. |
Your obligations as a seller after exchange
Once contracts are exchanged, you have several legal and practical obligations that run through to completion day. Taking these seriously protects you from a breach of contract claim.
Maintaining the property
Under the Standard Conditions of Sale, you are obligated to keep the property in the same physical condition as it was at the point of exchange. This means continuing routine maintenance, not stripping out any fixtures or fittings that are included in the sale, and reporting any damage (such as a burst pipe or storm damage) to your solicitor immediately. If the property suffers significant damage between exchange and completion, the buyer may have the right to reduce the purchase price or, in the worst case, withdraw from the sale.
Buildings insurance
Under the Standard Conditions of Sale (6th Edition), the risk in the property passes to the buyer on exchange. This means the buyer is technically responsible for arranging buildings insurance from the date of exchange. However, most solicitors advise sellers to maintain their own buildings insurance until completion day. If a fire or flood occurred between exchange and completion and neither party had adequate cover, it could create a complicated and costly dispute.
Preparing to vacate
The period between exchange and completion is your window to make all the practical arrangements for moving out. This includes booking a removal company, setting up Royal Mail redirection, notifying utility providers, and packing. For a full walkthrough of this period, see our guide on what happens between exchange and completion.
Not creating new encumbrances
You must not do anything that would affect the buyer's title to the property after completion. This means you cannot take out a new mortgage or charge against the property, grant new rights of way or easements, or enter into any agreements that would bind the property after the sale. Doing so would be a breach of the contract and could entitle the buyer to claim damages.
What happens if you cannot complete after exchange
If, as the seller, you are unable or unwilling to complete after exchange, the consequences are significant. This is deliberately so — the binding nature of exchange is what gives both parties certainty that the transaction will proceed.
- Penalty interest: If you fail to complete on the agreed date, you are liable to pay interest to the buyer at the contract rate (usually 4% above the Bank of England base rate or the base rate of a major clearing bank) for every day of delay.
- Notice to complete: The buyer's solicitor can serve a notice to complete, giving you 10 working days to finalise the sale. If you fail to complete within this period, the buyer can rescind the contract.
- Return of deposit plus damages: If the contract is rescinded due to your default, you must return the buyer's deposit in full and may be liable for their losses, including legal fees, survey costs, mortgage arrangement fees, and the difference in price if they have to buy a more expensive property elsewhere.
- Specific performance: In some cases, the buyer may seek a court order for specific performance, compelling you to complete the sale. This is a discretionary remedy but courts do grant it in property cases.
The financial exposure for a defaulting seller can be substantial. On a £350,000 sale, the buyer's losses could easily run to £10,000 to £20,000 or more in professional fees and price differentials, on top of returning the £35,000 deposit.
The Law Society exchange formulas
Solicitors in England and Wales use standardised formulas published by the Law Society to exchange contracts by telephone. There are three formulas, each designed for different situations.
| Formula | When it is used | How it works |
|---|---|---|
| Formula A | Simple transactions with no chain | Both solicitors already hold contracts signed by their own client. They agree to exchange over the telephone and then post the contracts to each other. |
| Formula B | Standard chains | One solicitor (usually the buyer's) undertakes to send their signed contract and the deposit that day. The exchange is binding from the moment the telephone call ends, even before the documents are posted. This is the most commonly used formula. |
| Formula C | Complex or longer chains | One solicitor acts as the coordinator, exchanging with each party in the chain in sequence. This ensures that all links in the chain exchange on the same day and no one is left committed without the rest of the chain also being bound. |
As a seller, you do not need to choose which formula is used— your solicitor will determine the appropriate one based on the structure of the transaction and any chain involved.
How to prepare for exchange day
While your solicitor handles the legal mechanics of exchange, there are several things you should do to ensure you are ready. For a more detailed walkthrough, see our guide on how to prepare for exchange day.
- Sign and return the contract promptly: Your solicitor needs your signed contract before they can exchange. Do not leave this sitting on the kitchen table for days. Sign it and return it as soon as you receive it.
- Confirm your completion date preference: Your solicitor will ask when you would like to complete. Common gaps between exchange and completion are 1 to 4 weeks. If you are buying another property, the completion dates for both transactions need to align.
- Book removals provisionally: Many removal companies book up weeks in advance, especially for Friday completions. Make a provisional booking as soon as the completion date is discussed, and confirm it once exchange has taken place.
- Arrange buildings insurance continuation: Contact your insurer to confirm your buildings insurance will remain in place until completion day. Do not cancel it on exchange.
- Review the completion statement: Your solicitor should provide a draft completion statement before exchange, showing exactly how the sale proceeds will be distributed. Check every figure and raise any queries before exchange, not after.
- Keep your phone available: On the day exchange is expected, keep your phone on and charged. Your solicitor needs to be able to reach you to confirm exchange and may need last-minute instructions, particularly around the completion date.
Exchange in a property chain
If you are part of a property chain — for example, you are selling your current home and buying another — exchange becomes more complex. Every party in the chain must exchange on the same day. This means your exchange depends not just on your buyer being ready, but on every other buyer and seller in the chain having completed their conveyancing, signed their contracts, and arranged their deposits.
The solicitors coordinate the exchanges sequentially, usually using Law Society Formula C. If one link in the chain is not ready, no one can exchange. This is why chains are the most common cause of exchange delays and one reason why chain-free buyers are considered more attractive by sellers. For a full breakdown of what to have in place before this point, see our conveyancing checklist for sellers.
What if exchange is delayed?
Exchange delays are common and can happen for many reasons: outstanding conveyancing enquiries, a slow local authority search, the buyer's mortgage offer not being ready, or another party in the chain holding things up. While frustrating, most delays are resolved within days or weeks.
The key risk of a delayed exchange is that neither party is committed until it happens. The longer the delay, the greater the chance of the sale falling through entirely. According to Propertymark, the most common window for sales to collapse is between weeks 8 and 16 of the conveyancing process — precisely when exchange is expected but has not yet occurred.
You can reduce the likelihood of delays by preparing your legal paperwork before listing, ordering searches upfront, and responding to your solicitor's enquiries immediately. Pine helps sellers complete these steps before they find a buyer, so that by the time an offer is accepted the contract pack is ready to go and the path to exchange is as short as possible.
Simultaneous exchange and completion
In some transactions, exchange and completion happen on the same day. This is most common in chain-free sales, auction purchases (where contracts are exchanged at the auction and completion follows within 28 days), and some new-build purchases.
Simultaneous exchange and completion eliminates the gap between becoming legally committed and handing over the keys, but it carries higher risk because there is no binding contract until the day itself. If a last-minute problem arises — a delayed bank transfer, a missing document — the sale could still fall through even though you are packed and ready to move. Your solicitor will advise whether this approach is suitable for your sale.
Sources and further reading
- The Law Society — Standard Conditions of Sale (6th Edition), exchange formulas, and conveyancing protocol guidance (lawsociety.org.uk)
- Solicitors Regulation Authority (SRA) — Client account rules for handling deposits and completion funds (sra.org.uk)
- HM Land Registry — Title registration, transfer deed guidance, and property ownership records (gov.uk/government/organisations/land-registry)
- Propertymark — Research on fall-through rates and transaction data for the UK property market (propertymark.co.uk)
- HomeOwners Alliance — Consumer guidance on exchange of contracts and buyer/seller rights (hoa.org.uk)
- Gov.uk — Guidance on buying and selling property in England and Wales (gov.uk)
Frequently asked questions
What does exchange of contracts mean for a seller?
Exchange of contracts is the point at which your property sale becomes legally binding. Both the buyer and seller sign identical contracts, the buyer’s solicitor sends the agreed deposit to your solicitor, and a completion date is fixed. After exchange, neither party can withdraw without facing serious financial penalties. For sellers, it means the buyer is now committed to purchasing your property at the agreed price.
Can I pull out after exchange of contracts?
Technically you can, but the consequences are severe. If you withdraw after exchange without a contractual right to do so, you are in breach of contract. You would be required to return the buyer’s deposit and could be sued for damages, including any additional costs the buyer has incurred such as survey fees, legal fees, the cost of alternative accommodation, and any difference in price if they have to buy a more expensive property. The buyer could also seek a court order for specific performance, forcing you to complete the sale.
How long before completion does exchange happen?
Exchange typically happens 1 to 4 weeks before the agreed completion date, with 2 weeks being the most common gap. In some chain-free or auction transactions, exchange and completion can happen on the same day (simultaneous exchange and completion). The gap between exchange and completion allows both parties time to make final arrangements such as booking removals, setting up utility transfers, and arranging mortgage drawdown. The exact gap is agreed between the solicitors during the exchange process.
What deposit does the buyer pay on exchange?
The standard deposit is 10% of the purchase price, held by your solicitor as stakeholder until completion. However, a reduced deposit of 5% is sometimes negotiated, particularly for first-time buyers or where the buyer has limited cash available. In a property chain, the deposit paid by the buyer at the bottom of the chain is often passed up through the chain so that not every buyer needs to provide the full 10%. If the buyer defaults after exchange, you are entitled to keep the deposit.
What time of day does exchange of contracts happen?
Exchange usually takes place during standard business hours, between 9am and 5pm on a working day. The actual exchange itself — the telephone call between solicitors — takes only a few minutes. However, in a property chain, all links in the chain must exchange on the same day, and the solicitors work through the chain sequentially. This means exchange might not be confirmed for your transaction until the afternoon if you are near the top of a long chain. Your solicitor will call you as soon as exchange is confirmed.
Do I need to sign anything on the day of exchange?
No, you will have signed the contract before exchange day. Your solicitor sends you the contract for signature days or sometimes weeks before the planned exchange date. You sign it and return it to your solicitor, who holds it until exchange is confirmed. On the day of exchange itself, the solicitors handle everything by telephone using one of the Law Society’s agreed exchange formulas. You do not need to be present at the solicitor’s office or sign anything on the day.
What happens if the buyer pulls out after exchange?
If the buyer fails to complete after exchange, they forfeit their deposit (typically 10% of the purchase price). Your solicitor can serve a notice to complete, giving the buyer 10 working days to finalise the purchase. If they still fail to complete, you can rescind the contract, keep the deposit, and resell the property to another buyer. You may also claim damages for any additional losses, such as the costs of remarketing the property or any shortfall if you eventually sell for a lower price.
Can the completion date be changed after exchange?
The completion date can only be changed after exchange if both parties agree to the variation in writing. Neither side can unilaterally move the date. If you need to change the completion date, your solicitor contacts the buyer’s solicitor to negotiate. If the buyer agrees, a deed of variation is drawn up and signed by both parties. If they do not agree, you must complete on the original date or risk being in breach of contract and liable for penalty interest and damages.
Is exchange of contracts the same as completion?
No, they are two distinct events. Exchange of contracts is when the sale becomes legally binding — contracts are signed, the deposit is paid, and a completion date is set. Completion is when the remaining purchase funds are transferred, the keys are handed over, and ownership of the property officially changes. There is usually a gap of 1 to 4 weeks between exchange and completion, though simultaneous exchange and completion on the same day is possible in some transactions.
What insurance do I need between exchange and completion?
You should maintain your buildings insurance on the property until completion day. Under the Standard Conditions of Sale (6th Edition), the risk in the property passes to the buyer on exchange, meaning the buyer is responsible for insuring from that point. However, if the property were damaged between exchange and completion and the buyer’s insurance did not cover it, there could be complications. Most solicitors advise sellers to keep their buildings insurance in place until the keys are handed over to avoid any gap in cover.
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