Gazumping and Gazundering: How to Protect Your House Purchase
An agreed house price is not legally binding in England and Wales until contracts are exchanged — leaving room for a seller to gazump you, or a buyer to gazunder a seller, right up until that point. This guide explains the risk and how to reduce it.
Gazumping occurs when a seller, having already verbally agreed a price with you, accepts a higher offer from a different buyer before contracts are exchanged. It can happen weeks into a purchase, after you have already paid for surveys and legal work, and is one of the most frustrating risks in the English and Welsh property system.
What Gazundering Is
Gazundering is the mirror image: a buyer lowers their offer, often close to the planned exchange date, knowing the seller has already committed emotionally and financially to the sale — and may be relying on the proceeds to buy their own onward property, creating pressure to accept the reduced price rather than restart the process.
Why It Is Legal: “Subject to Contract”
In England and Wales, a property transaction only becomes legally binding at exchange of contracts— when both parties' solicitors formally exchange signed contracts and a deposit is paid. Everything agreed before that point, including the headline price shown on the sale particulars, is technically “subject to contract” and can be changed or withdrawn by either side without legal consequence. This is different from the system in Scotland, where an accepted offer is generally binding much earlier in the process.
Lock-Out Agreements
A lock-out agreement(or “exclusivity agreement”) is a separate, legally binding contract in which the seller agrees not to negotiate with, or accept an offer from, any other buyer for a fixed period — commonly two to four weeks — while your purchase progresses. It does not compel the seller to actually complete the sale to you, but breaching it by accepting a rival offer during the locked-out period is itself a breach of contract, giving you a legal remedy.
Reservation Agreements for New Builds
New-build purchases commonly use a reservation agreement instead: you pay a (usually modest, sometimes refundable) reservation fee, and the developer agrees to take the property off the market for a set period while your purchase proceeds, with both sides committing to a target completion timetable. This offers materially more protection against being gazumped than the traditional resale process.
How to Reduce Your Risk
Instruct your solicitor and survey promptly, and respond quickly to any requests they make
Get your mortgage offer confirmed as early as realistically possible
Keep the estate agent and seller updated on progress to reduce their incentive to entertain other offers
Consider a lock-out agreement for higher-value or higher-risk transactions
Agree a realistic, mutually acceptable timetable to exchange with the other side from the outset
Use our Mortgage Calculator to keep your figures ready to move quickly once an offer is agreed.
FAQs
What is gazumping?
Gazumping happens when a seller accepts a higher offer from a different buyer after already verbally agreeing a sale price with you, but before contracts are exchanged. Because agreed prices are not legally binding until exchange in England and Wales, this is entirely legal, however frustrating.
What is gazundering?
Gazundering is the reverse: a buyer lowers their offer, often shortly before the planned exchange of contracts, using the seller's position further down their own onward chain as leverage. Like gazumping, it is legal but widely viewed as an unfair tactic.
Why is the agreed price not legally binding straight away?
Under the English and Welsh conveyancing system, a property sale only becomes legally binding at exchange of contracts, when both signed contracts are formally exchanged between solicitors and a deposit is paid. Everything agreed before that point — including the headline price — is technically "subject to contract" and can be changed or withdrawn by either side.
Can a lock-out agreement stop gazumping?
A lock-out agreement is a legally binding contract in which the seller agrees not to negotiate with any other buyer for a fixed period (commonly 2 to 4 weeks) while your purchase proceeds. It cannot force the seller to complete the sale, but it does make it a breach of contract for them to accept another offer during that window.
What is a reservation agreement, and does it help with new-build purchases?
A reservation agreement, common with new-build homes, is a paid arrangement in which the developer agrees to take the property off the market for a set period while your purchase proceeds, and both sides agree to complete within a set timeframe, with financial consequences for unreasonable withdrawal — offering more protection than the traditional resale process.
How can I reduce the risk of losing my purchase?
Move quickly on surveys, mortgage offers and searches, use a solicitor who responds promptly, keep the seller and estate agent updated on progress, consider a lock-out agreement for a higher-risk transaction, and try to agree a realistic timetable to exchange as early as possible.
Is gazumping insurance worth it?
Home buyer protection insurance can reimburse survey, valuation and legal fees already spent if a purchase falls through because you have been gazumped or the seller withdraws. It will not force the sale to go ahead, but it reduces the financial pain of starting again with a different property.
What should I do immediately if I have been gazumped?
Ask your solicitor to confirm the position in writing, decide quickly whether you can and want to match or beat the rival offer, and consider whether a lock-out agreement or a faster path to exchange would strengthen your position for future negotiations. There is no legal remedy that reverses a lawful gazump once it has happened.
Does putting an agreement in writing before exchange give any protection?
A basic written note of the agreed price is still only "subject to contract" and is not legally binding on its own. Genuine protection before exchange comes from a separate, standalone contract such as a lock-out or reservation agreement, drafted with that specific purpose in mind.
Can a buyer gazunder even if nothing has gone wrong with the property?
Yes — gazundering does not require a survey issue or a change in circumstances; a buyer can simply choose to reduce their offer close to exchange because they know the seller is under pressure to complete. It is a negotiating tactic rather than a response to new information, which is why it is widely seen as unfair.
Disclaimer: This guide is general information, not legal advice. Lock-out and reservation agreements should be drafted or reviewed by a qualified conveyancing solicitor to ensure they properly protect your position.
