Buying off-plan in London: how it works, the benefits and the risks

What 'off-plan' means

Buying off-plan means agreeing to buy a home before it is finished — often before construction has started — based on the plans, specification and a show apartment or CGI. You lock in the price on the day you exchange, and complete when the home is built.

How the money works

You pay a reservation fee, exchange contracts (usually within 28 days) with a deposit of around 10%, and the balance on completion. Some developers stage the deposit — for example 10% at exchange, a further 5% or 10% at set intervals — which suits buyers who want to spread the outlay before needing a mortgage. Your mortgage is arranged close to completion, since offers typically last six months.

Why buyers choose off-plan

• Price certainty: you fix today's price for a home delivered later, which matters in a rising market.
• Choice: the best units (higher floors, corner aspects, river views) are available early; late buyers get what's left.
• Time to save: a staged deposit gives you one to two years before completion to build savings or sell a current home.
• Brand-new specification with a 10-year warranty and a defects period — no chain, no refurbishment.
• For investors, London developments often complete in phases, letting you rent out or resell into a finished neighbourhood.

The risks — and how to manage them

• Delays: completion dates are estimates. Contracts include a 'long-stop' date after which you can withdraw; make sure yours is reasonable.
• Valuation gap: if values fall, the lender's valuation at completion may be below your agreed price, leaving you to fund the difference. Buy with a sensible deposit buffer.
• Developer risk: exchange only with established developers; your deposit should be protected under the warranty scheme (NHBC etc.) up to its limits.
• Specification changes: contracts allow minor variations. Get the specification in writing and confirm what is fixed.
• Mortgage timing: you cannot lock a mortgage rate years ahead. Plan for rates to move.

Who off-plan suits

Buyers who want a specific new home in a specific building and can wait; those needing time to gather a deposit; and investors targeting phased regeneration areas. If you need to move in the next few months, look at completed or 'ready to move in' stock instead — OpenHouse filters both.

Frequently asked questions

More guides

• How to buy a new-build home in London: the step-by-step process
• Stamp duty on new-build homes in London: 2026 rates explained
• Best areas in London for buy-to-let new-builds: how to choose
• Service charges on London new-build apartments: what they cover and what's typical