Buying and selling a house at the same time: chains, timing, bridging and Stamp Duty

A chain forms when each buyer needs to sell and each seller needs to buy, so all the deals have to move together. The Law Society's Conveyancing Protocol notes that a chain can only move as fast as its slowest member, or the last person to join it. Exchanges may need to happen at the same time across the whole chain, with completions on the same day.

The government's June 2026 home buying and selling reform roadmap says it takes around 120 days on average to complete once an offer is accepted. It plans to legislate for upfront 'sales packs' and for contracts that become binding earlier, but only when parliamentary time allows, so today's rules still apply.

Your conveyancer usually acts on both deals. They agree one completion date with everyone in the chain, then exchange your sale and your purchase on the same day. That way you are never bound to buy without also being bound to sell. On completion day the money moves up the chain. Your buyer's funds reach your conveyancer, who pays off your mortgage and sends the rest, plus your new mortgage and any savings, to your seller's conveyancer. A delay anywhere holds everyone up, so the keys can arrive late in the day.

You may not need fresh cash for the deposit. Under the Law Society's Standard Conditions of Sale the default deposit is 10% of the price. A seller who is buying another home to live in can use the deposit from their buyer as the deposit on that purchase. If your new home costs more, you'll need to top up the difference. On a £350,000 sale and a £450,000 purchase, a 10% deposit means £35,000 coming in and £45,000 going out. That leaves £10,000 to find, unless a lower deposit is agreed.

Don't book removals or give notice on anything until contracts have been exchanged and the completion date is fixed.

Only if you're comfortable with nothing being binding until the moment you complete. Simultaneous exchange and completion removes the gap between being committed and moving, and it is sometimes used when a chain is short or a deal has been delayed. The trade-off is uncertainty. You can't firmly book removals, lenders must release funds at short notice, and anyone can still pull out on the day without paying compensation.

A gap between exchange and completion gives everyone a firm date to plan around, and the deposit and contract protect against a last-minute withdrawal. The Standard Conditions of Sale set completion at 20 working days after exchange if no other date is agreed, but in practice the date is written into the contract.

Before exchange, anyone in the chain can pull out without paying compensation, and you usually lose what you've spent on searches, surveys and legal work. You could find a new buyer or a new home, or ask your seller to wait. You could also move into rented housing, so that you can buy without depending on a sale, or fund the purchase another way (see below). nidirect advises being prepared to arrange temporary accommodation.

After exchange the contract protects you. If a party doesn't complete on the agreed date, the other side can serve a notice to complete. Under the Standard Conditions of Sale, completion must then happen within 10 working days. A buyer who still doesn't complete can lose their deposit and be sued for losses. Completing late also means paying compensation at the contract rate. In Scotland this protection starts once the missives are concluded.

Yes, if you can fund the purchase without the sale money. You could use savings, a mortgage big enough to carry both homes for a while, or a bridging loan. A bridging loan is short-term borrowing secured on property and repaid when your old home sells. Interest and fees vary widely, so get the total cost in writing and be clear how you'll repay it if your sale takes longer than planned.

A bridging loan secured on a home that you or a close relative live in, or will live in, is generally a regulated mortgage contract, so the lender must be authorised by the FCA. Loans secured on property that neither you nor a close relative lives in, such as a buy-to-let, generally aren't regulated, and there are some narrow exclusions. Check any lender or broker on the FCA register.

If your current mortgage is portable, you may be able to move the deal to your new home rather than pay it off. The lender will reassess you and the new property, and any extra borrowing may be at a different rate. Check whether an early repayment charge applies if you can't port, or if your sale and purchase don't complete together. GOV.UK tells sellers to ask their lender about early repayment charges and any fees for moving the mortgage.

If you still own your old home at the end of the day your purchase completes, you'll usually pay the higher rates for additional properties, then claim the extra back once you sell. In England and Northern Ireland the SDLT higher rates are 5 percentage points above the standard rate in every band. They don't apply if your old main home is sold before, or on the same day as, your purchase.

Worked example: you're selling in England for £350,000 and buying for £450,000. Your sale is delayed, so you complete the purchase first. At standard rates the SDLT would be £12,500: 0% on £125,000, 2% on £125,000 and 5% on £200,000. At the higher rates it is £35,000: 5% on the first £125,000 (£6,250), 7% on the next £125,000 (£8,750) and 10% on the remaining £200,000 (£20,000). Sell your old home within 3 years and you can claim back £22,500. HM Land Registry's £150 online fee is the same either way.

You must claim within 12 months of whichever is later: the sale, or the filing date of the SDLT return. You can't claim if you or your spouse still own any part of the old home. HMRC's manual says that if the old home sells after completion but before the 14-day filing deadline, the return can be filed at standard rates. HMRC may also accept a later sale caused by exceptional circumstances, such as government restrictions or action by a public authority.

In Wales the LTT higher rates work the same way, with a 3-year window. To get the money back, amend your return within 12 months of the filing date, or claim within 4 years. In Scotland the 8% Additional Dwelling Supplement is refundable if you sell within 36 months and live in the new home. You amend your return within 12 months or claim within 5 years, and Revenue Scotland can't make exceptions for late sales. Try our Stamp Duty, LTT and LBTT calculators.

As for your old home, the final 9 months of ownership always qualify for Private Residence Relief if it was your main home. If it was your main home throughout and you sell within 9 months of moving out, you usually won't pay Capital Gains Tax on it.