Conditional Contracts for the Sale of Land: A Guide for Landowners, Developers and Buyers

For landowners and developers alike, a conditional contract can bridge the gap between a seller wanting a committed buyer and a buyer who is unwilling to take on the risk of proceeding before a critical condition has been met. 

Why use a conditional contract? 

A conditional contract is a legally binding agreement for the sale of land, but completion only takes place if specified conditions are satisfied. 

The most common example is a contract conditional on planning permission. A developer may agree to purchase a development land or a development site on the basis that it can first obtain satisfactory planning permission for its proposed scheme. If the planning outcome meets the agreed requirements, the contract becomes unconditional and the purchase must complete. 

For sellers, the benefit is that they have secured a buyer and agreed the principal terms of the sale at an early stage. For buyers, the arrangement reduces the risk of acquiring land that cannot be used in the way intended. 

How conditional contracts operate in practice

The contract will usually define: 

• the condition that must be satisfied; 

• who is responsible for seeking to satisfy the condition; 

• the timescales for doing so; 

• the evidence required to demonstrate satisfaction of the condition; and 

• the consequences if the condition is not satisfied. 

In a planning-related transaction, the buyer will often be responsible for preparing and submitting the planning application and pursuing any appeals where appropriate. The contract should also specify what level of planning consent will be regarded as satisfactory. This is often referred to as "satisfactory planning permission". 

If satisfactory planning permission is not obtained by the agreed deadline, the contract will usually allow the buyer — and sometimes the seller — to withdraw without further obligation, provided the condition has genuinely not been met on the terms defined in the contract. 

Careful drafting is important. If the planning requirements are vague, disagreements can arise as to whether the condition has in fact been satisfied. 

Conditional vs unconditional contracts

One of the key distinctions in development transactions is the difference between conditional vs unconditional contracts. 

Under an unconditional contract, exchange creates an immediate obligation on both parties to complete on the agreed completion date. The buyer cannot generally walk away simply because planning permission has not been obtained or the site is less attractive than anticipated. 

Under a conditional contract, completion depends upon the agreed condition being met. Until that happens, neither party is usually required to complete. The parties therefore allocate risk differently, which can make conditional contracts particularly attractive where future events may significantly affect the value or viability of a project. 

The choice between a conditional and unconditional contract will depend on the circumstances of the transaction, the bargaining strength of the parties, and the level of risk each side is prepared to accept. 

The importance of the long stop date

Most conditional contracts include a long stop date. 

This is the final date by which the condition must be satisfied. If the condition has not been met by that date, either one or both parties may have the right to terminate the contract. 

A long stop date protects both parties from being tied into an arrangement indefinitely. For example, if a planning application becomes delayed, is repeatedly amended, or remains undecided for an extended period, the parties need certainty as to when the contract can be brought to an end. 

The length of the long stop period will depend on the complexity of the proposed development and the planning risks involved. 

Conditional contracts and development land

Conditional contracts are particularly common where a landowner is selling land subject to planning permission or where a developer is buying land subject to planning permission. 

They can be used for: 

• residential development sites; 

• mixed-use schemes; 

• commercial development projects; 

• strategic land; and 

• land with redevelopment potential. 

For landowners, a successful planning application may significantly increase the value of the land. For developers, obtaining planning permission before committing to purchase can reduce commercial risk and improve access to development funding. 

The effectiveness of the arrangement depends largely on how the contract is drafted. Particular attention should be paid to the planning condition, the obligations on the buyer to pursue planning permission diligently, the long stop date, and the termination provisions if the condition cannot be satisfied. 

Conclusion

Conditional contracts can provide a practical solution where a future event, most commonly the grant of planning permission, is critical to the success of a transaction. They offer greater certainty than informal arrangements while allowing parties to manage development risk before completion occurs. 

Whether acting as a landowner or developer, careful drafting of the conditions, planning obligations and long stop mechanisms is essential to ensure that the contract achieves its intended commercial outcome. 

Conditional contracts for the sale of land: frequently asked questions

What is a conditional contract for the sale of land?

A conditional contract for the sale of land is a legally binding agreement under which completion only takes place if a specified condition is satisfied. The most common condition is the grant of planning permission, although other conditions can be used depending on the transaction. 

What is the difference between a conditional contract and an option agreement?

A conditional contract commits both parties to complete the transaction if the specified condition is satisfied. An option agreement, by contrast, grants one party the right, but not usually the obligation, to require the other party to enter into a sale of land on agreed terms. If the option holder exercises that right, the parties are then obliged to proceed with the transaction in accordance with the option agreement. 

What is a long stop date in a conditional contract?

A long stop date is the final date by which the relevant condition must be satisfied. If the condition has not been met by that date, the contract will typically allow one or both parties to terminate the agreement. 

How does a contract conditional on planning permission work?

The parties agree that completion will only occur if planning permission meeting the contract requirements is obtained. The contract usually sets out who will apply for planning permission, the standard of planning consent required, and what happens if permission is refused or granted subject to unacceptable conditions. 

What does "satisfactory planning permission" mean in a conditional contract?

"Satisfactory planning permission" refers to planning permission that meets the requirements specified in the conditional contract. If the planning permission meets the requirements specified in the contract, the condition will be satisfied, and the parties will generally be contractually obligated to complete the transaction. The definition may relate to matters such as the type of development permitted, the number of units, floor area, use class, density, viability, or the absence of onerous planning conditions. Because disputes can arise over whether planning permission is acceptable, the contract should define as precisely as possible what constitutes satisfactory planning permission. 

Is a deposit payable when exchanging a conditional contract?

Often, yes. However, the position depends on the agreed terms. Some conditional contracts require a deposit on exchange, whilst others provide for a reduced deposit or no deposit at all. The contract should clearly state whether a deposit is payable and the circumstances in which it may be returned. 

Next reads

• Industrial Property and Contamination Risk: Why a Clear Environmental Search May Not Tell the Whole Story 

• Getting to Completion: Negotiating a Commercial Lease in 2026 

Commercial Property law advice 

Our team of commercial lease solicitors in London advises landlords and occupiers on commercial leases, lease renewals, licence arrangements, business tenancies and property portfolio management across London, and throughout the whole of England and Wales. Whether you are taking your first business lease or expanding an existing portfolio, we can guide you through the process from Heads of Terms through to completion. 

Call 020 8858 6971 or email commercial@grantsaw.co.uk to discuss your circumstances. 

Subscribe to stay ahead of commercial property changes with Grant Saw Property Pulse. Get monthly updates, practical legal insights and invitations to briefings, helping you stay aware of important developments that may affect your property interests, transactions and clients. Sign up for our updates here. 

Disclaimer 

This article is for general information only and is not legal advice. Laws and guidance change and outcomes depend on facts. If you need advice on your situation, please contact us. Grant Saw Solicitors LLP is authorised and regulated by the Solicitors Regulation Authority. 

Last updated: 27 August 2026