Completion Date in Property Transactions
Completion is when legal ownership of a property transfers from seller to buyer. It is the day the balance of the purchase price is paid, keys are handed over, and — in most cases — the SDLT clock starts ticking.
Last verified: April 2026 | Source: GOV.UK
Key Takeaways
- •Completion is when legal ownership of the property passes to the buyer.
- •It usually sets the SDLT effective date — from which the 14-day payment deadline runs.
- •Your solicitor or conveyancer normally handles the SDLT return on completion day.
- •Completion is different from exchange — exchange is when the deal becomes binding.
- •In Wales, LTT must be filed within 30 days of completion (not 14).
In this article
What Is Completion
Completion is the final step in a property purchase. It is the day the transaction legally completes: the buyer becomes the registered owner, the purchase money is transferred, and the keys are released.
For SDLT purposes, completion is usually the effective date — the date from which stamp duty liability arises and the 14-day filing window opens.
What Happens on Completion Day
Final balance transferred
The buyer's solicitor sends the balance of the purchase price (minus any deposit paid at exchange) to the seller's solicitor.
Seller vacates
The seller hands over the keys and vacates the property.
Title deeds released
The seller's solicitor releases the title deeds and transfers them to the buyer's solicitor.
SDLT return filed
The buyer's solicitor usually files the SDLT return with HMRC on completion day or within 14 days.
Land Registry application
The solicitor registers the change of ownership at the Land Registry.
Completion vs Exchange
Exchange and completion are two separate legal events that are often weeks apart in a property transaction.
| Event | What it means | SDLT triggered? |
|---|---|---|
| Exchange of contracts | Legally binding agreement; deposit usually paid | No |
| Completion | Legal ownership transfers; keys handed over | Yes (14 days) |
SDLT on Completion
Your solicitor or conveyancer is responsible for filing an SDLT return with HMRC and paying any tax within 14 days of completion. In practice, most solicitors file on completion day itself and deduct the SDLT amount from the money you transfer to them.
SDLT rates are those in force on the completion date. If rates change between exchange and completion, the new rates apply. This is why some buyers rush to complete before a rate change takes effect.
Delayed Completion
If completion is delayed but the buyer has already substantially performed the contract (for example, moved in or paid over 90% of the price), the SDLT effective date may have already arisen. The 14-day clock runs from that earlier date, not from the eventual completion date.
A second SDLT return may also be required at formal completion if additional consideration is paid at that stage.
Wales: 30-Day LTT Deadline
In Wales, Land Transaction Tax (LTT) must be filed and paid within 30 days of the effective date (usually completion). This is twice as long as the SDLT deadline in England. Welsh buyers benefit from a longer window, but the return must still be filed even if no tax is due.
Official Government Source
For official SDLT guidance and deadlines:
Stamp Duty Land Tax — GOV.UKFrequently Asked Questions
What happens on completion date?
On completion, the balance of the purchase price is transferred from buyer to seller, legal title passes to the buyer, keys are handed over, and the buyer becomes the legal owner. The solicitor typically files the SDLT return on this date or within 14 days.
What is the difference between exchange and completion?
Exchange of contracts is when buyer and seller sign and swap contracts, creating a legally binding agreement. Completion is when the transaction actually finalises and ownership transfers. In most property purchases, there is a gap of days or weeks between exchange and completion.
What if completion is delayed?
If completion is delayed but the buyer has already substantially performed the contract (e.g. taken possession), the SDLT effective date may have already been triggered. Late completion does not extend the 14-day SDLT filing deadline if substantial performance has already occurred.
In this article
Emma Richardson, MRICS
Chartered Surveyor & Property Tax Specialist
Emma Richardson is a RICS-qualified Chartered Surveyor with over 12 years of experience in UK property taxation. She founded Calculate My Stamp Duty UK to help buyers understand the complex world of property transaction taxes.