Two of the more unsettling words a home mover might hear are gazumping and gazundering. One applies to buyers, the others to sellers, neither are usually welcome words to be heard but both acts are still legal in England and Wales.
In June 2026 the government set out plans that could reduce the risk over the coming years, though nothing has changed yet.
Here is what each term means, why they happen and how buyers and sellers across Chiswick, Hammersmith and Shepherd’s Bush can reduce the chances of being caught out.
What is gazumping
Gazumping is when a seller accepts a higher offer from a different buyer after already agreeing a sale and before contracts are exchanged.
The first buyer, who may have spent money on a survey, a mortgage arrangement and early legal work, is left with nothing.
Gazumping tends to happen when demand is strong and several buyers are chasing the same home, which encourages a seller to keep listening to offers even after saying yes.
What is gazundering
A lesser used term, and some might simply refer to it as renegotiation – Gazundering is when the buyer renegotiates, typically late in the process, often just before exchange, then reduces their offer.
The seller has to choose between accepting less or starting the search for a buyer again, usually after weeks or months of progress.
Pulling out and relisting can take time and be costly, some buyers use that pressure to renegotiate at the last minute.
Why both are legal in England and Wales
Neither gazumping or gazundering is against the law in England and Wales, and they can happen any time before contracts are exchanged.
In England and Wales a sale is not binding until contracts are exchanged, which can be many weeks and sometimes months after an offer is accepted.
Everything before that point is agreed subject to contract, so either side can change their mind or their price without legal consequence.
Government figures put the average purchase at around 120 days to complete and roughly one in three sales falls through before the finish line.
That long gap is the space where gazumping and gazundering happen. Scotland works differently, as formally accepted offers there become binding much earlier.
How common are they, and what drives them
Neither is an everyday event, partly because both create bad feeling and can sour a sale. When they do occur, the market usually explains the timing.
Gazumping is more common when prices are rising and buyers outnumber good homes, because sellers have the upper hand.
Gazundering appears more often when prices are flat or falling and buyers know a seller has few other options. In practical terms the pressure shifts to whichever side has more room to walk away.
What is the reform roadmap and will it make a difference?
On 19 June 2026 the government published its home buying and selling reform roadmap, aimed at the delays and failed sales that make gazumping and gazundering possible.
Two changes matter most here. Sellers would prepare an upfront sales pack before a home is listed, giving buyers key information from the start.
And once both sides commit, the proposed binding conditional contracts would make it far harder to walk away without a legitimate reason, with financial penalties for those who do.
However, it is important to note that these are currently simply proposals rather than law and they are being introduced in stages.
Guidance for agents and listings is due later in 2026, further consultation follows from 2027 and the main legislation for sales packs and binding contracts is expected by the end of this Parliament in 2029.
Binding contracts will only come in once sales packs are established. So whilst the direction of travel is clear, anyone buying or selling today the current rules still apply.
How buyers can reduce the risk of being gazumped
You cannot rule gazumping out, but you can make yourself the buyer a seller wants to keep. A few things help:
Move quickly
Speed is your main protection against gazumping. The longer the gap between an accepted offer and exchange of contracts, the more time there is for another buyer to appear with a higher bid.
You can shorten that gap by getting as much in place as possible before you offer: a mortgage agreed in principle, a solicitor instructed and ready, your deposit in place and your paperwork to hand.
Once the sale is agreed, stay responsive, return documents promptly and keep your side of the chain moving, because every week saved is a week a rival cannot use.
Ask the seller to take the property off the market once your offer is accepted
Once your offer is accepted, ask the seller to remove the listing and stop taking viewings.
A seller who agrees has effectively signalled they are committed to you, which is exactly the position you want.
Not every seller will say yes, particularly if your offer is on the low side or they are nervous about the chain, but it is always worth asking.
If they refuse outright, treat it as useful information about how secure the sale really is.
Build a good relationship with the seller and their agent
Gazumping is easier when a sale feels like a pure transaction and harder when there is a personal connection.
Sellers are less likely to drop a buyer they trust and get on with, even for a slightly higher offer, because most people would rather deal with someone reliable than gamble on a stranger.
Be straightforward, keep your word on timings and let the agent see you are serious and ready to proceed. That goodwill can be what tips a wavering seller in your favour.
If necessary, a lawyer can create exclusivity agreement
If you are especially worried about losing a home you really want, a solicitor can prepare a lock out or exclusivity agreement – this isn’t a particularly common occurrence as there is a cost involved.
This agreement gives you a short agreed period in which the seller cannot negotiate with anyone else, and it usually involves both sides putting down a small deposit that is returned once the sale completes.
When the market is competitive and moving at considerable speed, or on rare homes it can ensure the certainty for a buyer to reach exchange.
How sellers can reduce the risk of being gazundered
Sellers have fewer defences once a buyer decides to push, but preparation makes a difference:
Price realistically from the start
A sensible asking price does a lot to protect you from being gazundered.
When a home is priced fairly, a buyer has far less room to argue later that they are paying over the odds.
Overpricing can attract a buyer who offers high to secure the property, then chips the price down once you are committed and the process is well under way.
Getting the valuation right at the point of launching a home and basing figures on real local evidence removes much of the leverage a buyer might typically use.
Favour a strong buyer
The strength of your buyer matters as much as the size of their offer. A chain free buyer, or one who is well prepared, mortgage ready and clearly committed, has fewer reasons and fewer opportunities to reduce their offer late on.
A long or fragile chain, by contrast, creates more points at which things can go wrong and more excuses for a last minute renegotiation.
When you have a choice, a slightly lower offer from a secure buyer is often worth more than a higher one that is likely to wobble.
Keep the sale moving
Time is where gazundering lives, so the faster a sale progresses the less exposed you are.
Set an exchange date early so everyone has a target to work towards, and stay on top of enquiries, searches and paperwork rather than letting them drift.
Momentum keeps a buyer focused, while long unexplained delays give them room for second thoughts and a reason to question the price.
A good agent chasing both sides makes a real difference here.
If a buyer does gazunder, ask why before you react
If a buyer drops their offer, resist the urge to respond straight away.
Ask for their reasons first, because they are not always simply trying it on.
A survey may have flagged a genuine problem, or their own funding or chain may have shifted, and understanding the cause tells you whether a sensible compromise is possible.
If the reduction is opportunistic and the numbers no longer work for you, you remain free to hold firm or walk away, so decide from a position of information rather than panic.
How a good agent reduces the risk
Most of what protects a mover comes down to momentum and judgement, and this is where an experienced local agent earns their place.
A good agent qualifies buyers properly before a sale is agreed, keeps both solicitors moving, spots when a deal is drifting and steps in early.
They also know their area, so they can price a home sensibly and read whether an offer is solid or shaky.
Across three connected but distinct markets like Chiswick, Hammersmith and Shepherd’s Bush, that local knowledge is often the difference between a sale that completes and one that unravels.
Thinking of buying or selling in West London?
Gazumping and gazundering are far less likely when a sale is handled well from the first viewing through to exchange.
If you are planning a move in Chiswick, Hammersmith or Shepherd’s Bush and want an agent who will keep things on track, get in touch with the Horton and Garton team.
