When buying a new-build home, you may exchange contracts before the property is finished and before an exact completion date is known. This arrangement may be described as exchange on notice or completion on notice, although the wording in your contract may differ.
In simple terms, you exchange contracts and normally become legally committed to the purchase before the completion date is confirmed. Once the relevant contractual requirements have been met, the seller may serve notice requiring you to complete within the period stated in your contract.
This guide explains how the process usually works when buying a new-build home in England. Your solicitor or licensed conveyancer should explain the terms that apply to your purchase.
How is exchange on notice different from a standard exchange?
In a standard property purchase, the buyer and seller usually agree a fixed completion date when they exchange contracts. Exchange normally makes the agreement legally binding, with the purchase completing on the agreed date.
A new-build home may still be under construction when contracts are exchanged, so it might not be possible to confirm the completion date at that point. Instead, the buyer and seller enter into a binding contract without fixing the exact date on which completion will take place.
Once the requirements specified in the contract have been met, the seller may be entitled to serve notice requiring the buyer to complete within the contractual notice period. This is normally handled through the parties’ solicitors or conveyancers.
The GOV.UK guide to transferring ownership when buying a home provides further information about exchanging contracts, completion and conveyancing.
The exchange-on-notice process
The exact process will depend on your reservation agreement and purchase contract, but it will usually involve the following stages.
1. You reserve your chosen home
You normally pay a reservation fee and receive information about the home, proposed purchase and expected construction timetable.
Your reservation agreement will set out the terms of the reservation, including how the reservation fee is treated.
You may also receive an estimated build window. This can help you plan, but it should not be treated as a guaranteed completion date unless your contract says otherwise.
2. Your conveyancer reviews the purchase
Before exchange, your solicitor or licensed conveyancer will review the contract and supporting legal documents.
They should explain:
- what must happen before notice can be served
- how much notice you will receive
- how the completion deadline will be calculated
- whether the contract contains a long-stop date
- what could happen if either party does not complete
- how the arrangement may affect your mortgage, tenancy or related property sale
Ask about anything you do not understand before authorising your conveyancer to exchange contracts.
3. Contracts are exchanged
Once the legal work is complete and you are ready to proceed, contracts can be exchanged. You will usually need to pay an exchange deposit or another amount required under your purchase arrangement.
The purchase will normally become legally binding at this point, even though you do not yet have an exact completion date.
Before exchanging, check that your mortgage, deposit and other finances have been considered. If you are selling another property or renting your current home, tell your conveyancer how these arrangements are connected to your new-build purchase.
4. Construction continues
The developer continues building the home and working towards the completion requirements stated in the contract.
You may receive progress updates or revised estimates during this period. These can help with planning, but they do not replace the formal contractual notice.
5. Notice requiring completion is served
Once the relevant contractual requirements have been met, the seller may be entitled to serve notice requiring completion within a specified period.
Your conveyancer should confirm:
- the completion deadline
- the money you need to provide
- any action required in relation to your mortgage or completion contribution
- any documents or final steps still outstanding
The notice period and the way it is calculated will be set out in your contract.
6. The purchase completes
During the notice period, your conveyancer completes the remaining legal and financial work.
On completion day, your conveyancer transfers the required money to the seller’s solicitor. Once completion has been confirmed, arrangements can be made for you to receive the keys.
Read our guide to what happens on completion day for more information about the final stage.
When the purchase becomes legally binding
The purchase normally becomes legally binding when contracts are exchanged, not when notice requiring completion is served.
This means you are committing to buy the home before you know the exact completion date. The seller is also bound by the terms of the contract.
If either party later fails to complete in line with the contract, there may be financial or legal consequences. Your conveyancer should explain the commitments being made and what could happen if either party does not meet its contractual obligations.
Your contractual notice period
There is no single notice period for every new-build purchase. The length of the period and the way it is calculated will be stated in your contract.
A notice period may use working days or calendar days, which can result in different completion deadlines. Do not rely on a commonly quoted period, such as 10 or 14 days, without checking the terms of your purchase.
Before exchange, make sure you understand:
- how long the notice period is
- whether it uses working days or calendar days
- what must happen before notice can be served
- how the completion date will be calculated
- what you must do when notice is received
- what could happen if you cannot complete by the deadline
Your conveyancer should explain these points before you authorise the exchange of contracts.
What is a long-stop date?
A new-build contract may include a long-stop date. Depending on the wording of the contract, certain rights may arise if specified completion requirements have not been met by that date.
A long-stop date is different from an estimated build window:
- an estimated build window indicates when the home is expected to be ready
- a long-stop date is a contractual provision that may apply if specified requirements have not been met by a particular date
The rights attached to a long-stop date, the conditions that must be met and what happens to money already paid will depend on the contract.
A change to the estimated build date does not automatically mean you can withdraw from the purchase. Ask your conveyancer whether your contract includes a long-stop date and what it means for you.
If construction is delayed
Construction timetables can change, so an expected completion date may move after contracts have been exchanged.
A delay could affect:
- the validity of your mortgage offer
- the sale of your current property
- when you end a tenancy
- temporary accommodation
- removal arrangements
- when your contribution towards completion is required
Your contractual rights will depend on the terms of your purchase and whether a relevant deadline has been reached.
If you are renting, be cautious about ending your tenancy based only on an estimated build date. If you are selling another home, make sure your conveyancer understands how the two transactions are connected.
If your mortgage offer expires before completion
Several months may pass between exchange and completion when a home is bought before construction has finished.
Check the expiry date of your mortgage offer and keep your lender or mortgage adviser informed if the expected timetable changes.
If your offer cannot be extended, you may need to make a new mortgage application. The amount available, interest rate and other terms could be different, and a new offer is not guaranteed.
Tell your conveyancer and mortgage adviser promptly if your financial or personal circumstances change. Do not assume that your existing mortgage offer will remain available until the home is ready.
Preparing for notice to be served
The exact moving date may remain uncertain until formal notice is served. Until then, keep your mortgage, current accommodation, completion contribution, removals and any related property sale under review.
When notice is served, your conveyancer should confirm the completion deadline and what you need to do. This may include:
- checking with your lender or mortgage adviser that mortgage funds can be released
- transferring your remaining contribution when requested
- providing outstanding documents
- meeting final lender requirements
- arranging removals
- reviewing the final information about your new home
Before notice is served, ask your conveyancer when your contribution is likely to be required and allow enough time for any transfers or withdrawals.
Continue to monitor the expiry date of your mortgage offer and respond promptly to your conveyancer, lender, mortgage adviser or sales contact.
Exchange on notice and Shared Ownership
If you are buying through Shared Ownership, ask whether the purchase arrangement changes any exchange or completion requirements.
A Shared Ownership purchaser buys an initial share of the home and enters into a lease with the landlord. The legal documents, funding requirements and parties involved may therefore differ from an outright private sale.
Your solicitor or licensed conveyancer should explain the documents and requirements that apply to your purchase before contracts are exchanged.
Points to discuss with your conveyancer
Before authorising your solicitor or licensed conveyancer to exchange contracts, make sure you understand:
- the length of the notice period
- whether the period is measured in working days or calendar days
- the requirements that must be met before notice can be served
- whether the contract contains a long-stop date
- any rights that could arise if the long-stop date is missed
- the possible consequences if you cannot complete by the deadline
- what to do if your mortgage offer may expire before completion
- how the arrangement could affect your tenancy or related property sale
- whether Shared Ownership changes any exchange or completion requirements
Ask your conveyancer to explain anything that is unclear before contracts are exchanged.
Find a new-build home
Explore new-build homes available through Shared Ownership and private sale with Guinness Homes.
Important information
This article provides general information about exchange on notice when buying a new-build home in England. It is not legal, financial or mortgage advice and does not take account of your individual circumstances.
The terminology, requirements, notice period, long-stop provisions and completion arrangements will depend on your contract. Ask your solicitor or licensed conveyancer to explain these terms and the possible consequences before you exchange contracts.
If you are using a mortgage, discuss the expected completion timetable and validity of your mortgage offer with your lender or mortgage adviser.
This information was checked on 22 September 2026. Processes, guidance and contractual terms may change after publication.
