Exchange and completion: what happens on the day

Exchange and completion are the two key steps that turn an agreed sale into a finished purchase. Exchange is the point where the deal becomes legally binding. Completion is when the money is transferred and the buyer can take possession. The steps after completion include stamp duty paperwork and registration at HM Land Registry.

What exchange means

At exchange, both parties sign the contracts and the solicitors swap the signed copies. Before this point, either side can decide not to go through with the sale. After exchange, the agreement is legally binding. The buyer’s deposit is paid at exchange through the solicitors, and Citizens Advice says it is often 10% of the purchase price, although it can vary. The Law Society says a buyer who pulls out after exchange could lose the deposit and may also have to pay other legal costs.

What completion involves

Completion happens when the buyer’s solicitor sends the rest of the purchase money to the seller’s solicitor, after deducting the deposit already paid. Once the money has been received and both solicitors have used the Code for Completion, the keys are released. The Law Society says this is usually around late lunchtime.

Stamp duty and registration after completion

After completion, an SDLT return must be sent to HMRC and any tax due must be paid within 14 days. GOV.UK says solicitors usually file the return and pay on completion day, and that penalties and interest apply if this is late. The buyer’s solicitor then applies to HM Land Registry to register the buyer as owner and the lender as mortgagee. The registration application must be made within 2 months of completion. HM Land Registry said in May 2026 that over half of transfer applications take 16 weeks and most complete in about 8 months, although legal ownership rights are secured from the moment the application is received.

How long exchange to completion takes

Citizens Advice says the period from exchange of contracts to completion usually takes up to four weeks, although it can be earlier. The same source says the earlier stage, from offer accepted to exchange, can take up to seven weeks.

Key facts

Source: The Law Society - Buying a home — Guidance checked August 2026

Source: The Law Society - Buying a home — Guidance checked August 2026

Source: The Law Society - Buying a home — Guidance checked August 2026

Source: Citizens Advice - Buying a home — Guidance checked August 2026