What Can Go Wrong Between Exchange and Completion?

Once contracts are exchanged, your sale is legally binding — so the list of things that can go wrong shrinks dramatically. It does not reach zero. The realistic risks in the exchange-to-completion gap are: your buyer failing to get the money to their solicitor in time; a lender pulling the mortgage offer before funds are drawn down; someone further up or down the chain completing late and missing the banking deadline; damage to the property while it sits empty; and death or bankruptcy of a party. A buyer who walks away after exchange normally forfeits their 10% deposit, pays interest at the contract rate, and can be sued for any shortfall on a resale.

Most sellers spend the whole of their sale terrified of the buyer disappearing. That fear is well founded right up until the moment contracts are exchanged. After that, the anxiety usually outlives the actual risk by several weeks.

It is worth being precise about what changes and what doesn't, because "legally binding" gets thrown around as though it means "guaranteed". It doesn't. It means that if it falls apart, someone pays. That's a very different promise.

What actually changes the moment you exchange

Up to exchange, everything is provisional. Your buyer can renegotiate on a whim, gazunder you on a Friday afternoon, or simply stop answering the phone. You can accept a higher offer from someone else. Nobody owes anybody a penny.

At exchange, two identical signed contracts are swapped between the solicitors, a completion date is written in, and the buyer's deposit – conventionally 10% of the purchase price, though 5% is common and negotiable – is transferred to your solicitor to be held. From that second, both of you have a legal obligation to complete on the agreed date.

So the question stops being "will this fall through?" and becomes "what happens if someone can't perform?" That is a much narrower, much more manageable set of problems.

Risk one: the buyer cannot raise the money on the day

This is the big one. Not cold feet – cash flow.

Your buyer's solicitor has to draw down the mortgage advance from the lender, combine it with the buyer's own funds, and send the whole lot to your solicitor by CHAPS. Every part of that chain has a cut-off. Lenders usually want several working days' notice to release funds. CHAPS payments have to be instructed by early afternoon to land the same day.

Miss any of those and the money simply isn't there at 1pm on a Friday, and everyone stands around with vans on the drive.

Common causes, in rough order of how often they actually happen:

• The mortgage offer expired. Offers typically run for three to six months from issue. A long gap between offer and completion – new-build, probate, a slow chain – can run one out. Re-issuing takes days, sometimes weeks, and may need a fresh credit check.
• The lender withdrew the offer. Lenders re-run credit checks shortly before drawdown. A buyer who takes out car finance, changes jobs, goes on probation, misses a payment or racks up a credit card between exchange and completion can lose their offer outright. Buyers are rarely told this clearly enough.
• The deposit money is stuck. Gifted deposits from family, funds sitting in a fixed-term account, money coming from abroad, or part of the price relying on the sale of something else – shares, another property, a business – all bring timing risk.
• Anti-money-laundering checks stall. A large unexplained credit into the buyer's account triggers source-of-funds questions their solicitor must resolve before they can send anything.

None of these mean the buyer is dishonest. They mean the buyer is late. Legally, though, late is a breach.

Risk two: the chain completes out of order

If you are in a chain, your completion is not really yours. Everyone in the chain has to exchange on the same day and complete on the same day, with the money flowing from the bottom upwards.

The first-time buyer at the bottom sends money to the person above, who sends it on, and so forth. If any one solicitor is slow – a paralegal off sick, a payment instructed at 2:40pm instead of 11am, a bank query on a large transfer – the delay does not stop with them. It cascades to every household above.

What that looks like in practice: removal vans loaded, keys held by the agent, families sitting in a car park waiting on a text. If the money lands after the bank cut-off, completion rolls to the next working day and everybody finds a hotel or a friend's spare room.

Delay is not the same as collapse. In the overwhelming majority of these cases the money arrives the next morning and the sale completes a day late, with the late party liable for interest and reasonable costs. It is expensive and miserable, not fatal.

Risk three: the property is damaged before the keys change hands

This is the part that catches people out, and the standard advice you will read elsewhere is often simply out of date.

Under the Standard Conditions of Sale (5th edition), which govern most residential sales in England and Wales, condition 5.1.1 puts the property at the buyer's risk from the date of the contract – that is, from exchange, not completion. The seller is under no general obligation to keep insuring it. That is a change from the fourth edition, and plenty of guidance online still hasn't caught up.

The seller does still have to hand the property over in essentially the same physical state as at exchange, fair wear and tear aside. So you cannot strip out the fitted kitchen you agreed to leave, and you cannot stop maintaining the place.

What you should actually do is straightforward: keep your buildings insurance running until completion, even though you may not be legally obliged to. The cost of a few extra weeks' premium is trivial next to the alternative. Two overlapping policies are not a problem; a gap is.

Things that genuinely go wrong here: a burst pipe in an empty house in January, a storm taking tiles off, a break-in through a back window after the furniture has gone, an escape of water from the flat above. If the damage is significant, the buyer's lender may re-inspect and, in the worst case, refuse to release funds until it is repaired.

Also worth knowing: most standard home insurance policies restrict cover once a property has been unoccupied for 30 or 45 consecutive days. If you are moving out well before completion, call your insurer and tell them. An unoccupied-property endorsement is cheap. A declined claim is not.

Risk four: someone dies, or goes bankrupt

Rare, but real, and worth stating plainly because it frightens people disproportionately.

If the buyer dies between exchange and completion, the contract survives. The obligation passes to their estate and their personal representatives complete the purchase. In practice this takes time and often needs a grant of probate, which is currently running at roughly eight to sixteen weeks. Everyone usually agrees an extension rather than trying to enforce a notice to complete against a grieving family.

If the seller dies, the same principle applies in reverse: the estate is bound to complete. Again, delay is the practical consequence.

If the buyer is made bankrupt, the trustee in bankruptcy takes over their affairs and will normally disclaim an onerous contract. The lender will pull the mortgage offer immediately. This is one of the few post-exchange scenarios where the sale genuinely dies and you may struggle to recover much, because there is rarely anything left to sue for. The deposit – if you insisted on a proper one – is usually the only money you see.

What happens when a buyer simply does not complete

Here is the machinery, because it is more decisive than most sellers expect.

If completion does not happen on the contractual date, the defaulting party is in breach immediately and starts accruing interest at the contract rate. Under the Standard Conditions that is typically 4% above the base rate of a named clearing bank. With the Bank of England base rate at 3.75% as of September 2026, that is around 7.75% a year on the full purchase price, charged daily.

Your solicitor then serves a notice to complete. This makes time of the essence and gives the buyer ten working days to perform. It is a serious document and it concentrates minds; the majority of defaulting buyers find the money inside that window.

If they still do not complete, you can rescind the contract. At that point you may:

• forfeit the deposit held by your solicitor (normally 10%, which is exactly why accepting 5% weakens your position);
• keep any interest accrued;
• put the property back on the market and sell to someone else;
• claim damages for your losses – wasted costs, bridging interest, and crucially any shortfall if the resale price is lower.

The deposit is capped compensation, not a windfall. If your losses come to less than the deposit, a court can order part of it returned. If they come to more, you can pursue the balance – assuming the buyer has anything worth pursuing, which is the practical catch.

A worked example

Say you exchange on a £310,000 house with a 10% deposit of £31,000 and a completion date of 14 September. Your buyer's lender withdraws its offer four days beforehand after a failed credit check, and completion does not happen.

• Days 1–10: Interest runs at the contract rate. At 7.75% on £310,000 that is roughly £65.82 a day, so about £658 over ten days. Your solicitor serves a notice to complete on day one.
• Day 11: Still no funds. You rescind and forfeit the £31,000 deposit.
• Weeks 2–16: You re-market. The property has "been around" now and the buyer pool has thinned. You accept £298,000 – a £12,000 shortfall.
• Your position: £31,000 deposit, less a £12,000 shortfall, less perhaps £2,500 of wasted fees, re-marketing costs and four months of extra mortgage interest. On paper you are covered. In reality you have lost four months and a great deal of sleep, and if the buyer disputes the forfeiture you may end up arguing about the surplus.

Now run the same scenario with a 5% deposit of £15,500. The shortfall and costs eat almost the entire deposit and you are chasing a buyer who has already proved they have not got the money. That is why you should push hard for a full 10% deposit at exchange, and treat a request to reduce it as information about your buyer's finances rather than a bit of harmless admin.

When the seller is the one who cannot complete

It happens, and it is usually not deliberate. The onward purchase collapses and the seller has nowhere to go. A tenant has not vacated. A last-minute title problem surfaces – an unregistered right of way, an unapproved extension, a charge nobody spotted.

The buyer's remedies mirror yours: interest at the contract rate, a notice to complete, then rescission with the deposit returned with interest, plus a damages claim. A buyer who has sold their own home and been left homeless has a meaningful claim for storage, temporary accommodation and abortive costs. Specific performance – a court order forcing the sale through – is also available, and unlike most contracts courts do grant it for land, because no two properties are identical.

The blunt version: do not exchange until you are genuinely certain you can hand over vacant possession on the date written into the contract. Being pushed into exchanging by an agent chasing a month-end target is not a reason to take that risk.

How to make completion day boring

Almost every post-exchange disaster traces back to something that could have been checked a fortnight earlier. A short list, in order of value:

1. Ask your solicitor to confirm the buyer's mortgage offer is issued, valid, and not expiring before the completion date. Do this before you exchange, not after.
2. Insist on a 10% deposit. If the buyer can only manage 5%, ask why, and take the answer seriously.
3. Avoid Fridays and the last working day of the month. They are the busiest days for conveyancers and banks, which is precisely when payment queues cause delays.
4. Give yourself a sensible gap. One to two weeks between exchange and completion is enough for removals and utilities without leaving so long that mortgage offers and searches start ageing.
5. Keep your buildings insurance on, and tell the insurer if the property will be empty for more than a month.
6. Warn your buyer, through the agent, not to touch their credit. No new cards, no car finance, no job change until the keys are theirs. Many buyers have no idea their offer can be pulled at the last minute.
7. Read the fixtures and fittings form again. Arguments over a removed shed, a taken light fitting or a dug-up shrub cause more completion-day grief than anything except money.
8. Collect the phone numbers. Your solicitor's direct line, your agent's mobile, the removal firm. On the day, whoever reaches a human first gets sorted first.

When the exchange-to-completion risk is the wrong risk to worry about

Everything above assumes a conventional open-market sale, which for most people is the right route. It usually gets the best price, and the post-exchange failure rate is genuinely low.

The risk you should actually be weighing is not the exchange-to-completion gap. It is the sixteen to twenty-four weeks before exchange, when your buyer can vanish for nothing. That is where around one in four agreed sales die. If you are selling against a repossession deadline, a divorce settlement, an emigration date, a bridging loan winding down, or a probate property draining money every month, that pre-exchange window is the thing that can genuinely ruin you.

That is the case for a genuine cash buyer. A real one buys with its own funds, so there is no mortgage offer to withdraw, no chain, no lender re-inspection, and completion typically lands in 7 to 28 days. The trade-off is honest and unavoidable: expect 75–85% of open-market value. Anything advertised above roughly 82% deserves proper scrutiny, because the most common complaint in this sector is a price cut arriving late in the process, once the seller is committed and out of options.

A cash sale is the wrong answer if you have time, a decent property in a liquid area and no deadline. Paying 15–25% for speed you do not need is simply expensive. Be honest with yourself about which of those two situations you are actually in.

How to check a cash buyer is real

If you do go down that road, four checks separate the genuine firms from the brokers who will hawk your details around:

• Proof of funds. Ask for a current bank statement or a solicitor's certificate. A genuine buyer produces it without fuss. A broker changes the subject.
• Membership of the National Association of Property Buyers (NAPB) and registration with The Property Ombudsman (TPO). TPO membership means you have somewhere to complain, with awards of up to £25,000. Check the register yourself rather than trusting a logo in a footer.
• A written offer that sets out the basis of valuation, including what would have to happen for it to be reduced. Vagueness here is the single best predictor of a late price cut.
• No fees, no tie-in, no exclusivity agreement. A legitimate buyer covers your legal costs and does not lock you in.

Ready Steady Sell was set up by Lisa Hayes for exactly this reason: the quick-sale market is full of firms that are excellent at marketing and poor at completing, and sellers rarely have the time or information to tell them apart. Our comparison of UK house-buying companies and our industry data exist to be read before you talk to anyone, not after.

Frequently asked questions

How long is the gap between exchange and completion?

Usually one to four weeks, with two weeks the most common. It is negotiable and written into the contract. Same-day exchange and completion is possible where there is no chain and no mortgage – a cash purchase, for instance – but it removes any buffer for removals, so most people leave at least a few days.

Can a buyer pull out after exchange of contracts?

Physically yes, freely no. They would be in breach of a binding contract. You can serve a notice to complete, charge interest at the contract rate, and after ten working days rescind, forfeit the deposit and sue for any shortfall on resale. In practice the cost is so high that almost no buyer does this deliberately – the ones who fail to complete are usually the ones who genuinely cannot.

Can the price be renegotiated after exchange?

Not unilaterally. The price is fixed in the contract. Both parties can agree to vary it – occasionally sellers accept a small reduction to keep a stalled completion alive rather than start again – but you are under no obligation whatsoever to entertain it. Gazundering after exchange is not a thing.

Who insures the property between exchange and completion?

Under the Standard Conditions of Sale (5th edition) the risk sits with the buyer from exchange, and their lender will insist on cover from that date. Even so, keep your own buildings policy running until completion. It costs very little and closes the gap if there is any argument about who was covering what. Tell your insurer if the property will be standing empty for more than about 30 days.

What if my buyer's mortgage offer expires before completion?

They must apply for an extension or a re-offer, and the lender will normally re-run affordability and credit checks. This is one of the strongest arguments for keeping the exchange-to-completion gap short. Your solicitor should confirm the expiry date before you exchange – if it is tight, that is a reason to bring the completion date forward.

What happens if completion is just a few hours late?

Usually nothing dramatic. If the money misses the banking cut-off, completion moves to the next working day. The late party owes interest at the contract rate for the delay and, in principle, reasonable costs such as a night in a hotel or a day's storage. Keep the receipts. Solicitors settle most of these between themselves without anyone going near a court.

The short version

After exchange you are far safer than you feel. The genuine risks are late money, a withdrawn mortgage offer, chain timing, damage to an empty house, and the rare tragedies of death and bankruptcy. Nearly all of them are managed by three unglamorous habits: insist on a 10% deposit, keep the gap to a couple of weeks, and do not complete on a Friday.

If the part that worries you is the four to six months before exchange – the stretch where a buyer can walk away for free – that is a different problem with a different solution. Start with a realistic idea of what your house is worth, get familiar with the terminology in our property jargon guide, and if speed and certainty genuinely matter more to you than the last 20% of the price, read how cash house buyers and fast house sales really work before you commit to anybody.