Commercial tenants sometimes ask to bring in another occupier or transfer their lease to a new business. Your tenant may do this for several reasons, including restructuring, changes in trading conditions, or a need to reduce space. Requests of this kind can create uncertainty for you and raise important questions about your control over the property, your exposure to risk, and the long-term management of your investment and your relationship with your tenants. This guide explains how a commercial sublet agreement and a property assignment work in practice, and how you can respond in a way that protects the value of your asset.
It’s important to note that commercial leasing terminology differs from that used in residential sublettings. In a commercial context, the occupier is referred to as the tenant or lessee, and the agreement itself is a commercial lease. If your tenant grants a further lease out of their own interest, this creates an underlease and is treated as subletting. By contrast, if they transfer their entire leasehold interest to another party, the transaction is known as an assignment. This guide uses these terms consistently, so the legal framework is easy to follow.
This article concerns commercial leases in England and Wales. Scotland has a distinct assignation and sub-lease framework, with different terminology and processes, so landlords dealing with Scottish premises should take separate advice.
The aim of this article is to give you a clear, practical overview of how subletting and assignment operate, what tenant subletting rights may exist under your lease, and how you can respond to requests in a way that supports effective property management.
Summary
This guide covers:
- Defining Subletting and Assignment
- A Commercial Tenant's Right to Sublet or Assign
- Landlord's Consent
- What Constitutes Unreasonable Withholding of Consent?
- Conditions for Consent
- The Subletting Process
- The Assignment Process
- Landlord's Remedies for Unauthorised Subletting or Assignment
- Best Practices for Landlords
Defining Subletting and Assignment
Subletting and assignment are two different ways your tenant may deal with their commercial lease. Subletting creates a layered structure of occupiers, while assignment transfers the lease entirely to a new tenant. The distinction affects who you deal with and who remains liable under the lease.
Commercial Sublet Agreement
Subletting involves your tenant granting a new lease out of their existing one. You remain in contract with the original tenant under the headlease, while the original tenant becomes landlord to the undertenant. You do not usually have a direct contractual relationship with the undertenant, and the original tenant remains responsible for complying with the headlease.
Property Assignment
Assignment transfers your tenant’s entire interest in the lease to a new party. The assignee steps into the outgoing tenant’s position and becomes directly liable to you. The outgoing tenant may still have obligations, for example under an authorised guarantee agreement, but the day-to-day relationship is now between you and the assignee.
Key Difference for Landlords
The key difference for you is control. Subletting keeps the original tenant in place, while assignment changes the identity of the tenant entirely. This affects the financial reliability of the occupier, the management of the building, and the long-term value of your investment. A new occupier with weaker financial standing may increase the risk of rent arrears, while a business with heavier use may place strain on shared areas or insurance arrangements.
A Commercial Tenant's Right to Sublet or Assign
Your tenant’s right to sublet or assign a commercial lease depends on the lease terms. Many leases restrict these dealings and require your written consent. Where a qualified consent clause applies, the law may prevent you from refusing or delaying consent without good reason.
The Lease
Start by checking the alienation provisions in the lease. If the lease does not restrict assignment, underletting or sharing occupation, the tenant may have wider freedom to deal with the lease. Most modern commercial leases contain detailed alienation clauses that set out whether subletting or assignment is permitted and on what terms.
Alienation Clauses
These clauses may allow assignment of the whole but prohibit assignment of part. They may allow subletting of the whole or part, but only on terms that mirror key provisions of the headlease. They may also restrict sharing of occupation, for example limiting it to group companies only.
The Law
Even where your lease allows subletting or assignment with your consent, statute may impose additional duties. In many cases, you must not unreasonably withhold or delay consent to your tenant’s request. This duty is implied by the Landlord and Tenant Act 1927 and reinforced by the Landlord and Tenant Act 1988.
A well-drafted lease gives clarity about what is permitted and helps manage expectations when your tenant raises questions about subletting rights or property assignment.
Landlord's Consent
You may refuse consent to commercial subletting or property assignment only where the lease gives you control over the proposed dealing and your reasons are genuine, reasonable where required by law, and connected with the landlord-and-tenant relationship. Your tenant must apply in writing, and you must respond within a reasonable time. Statute sets clear duties on how consent must be handled.
Tenant’s Request
Where your lease requires your consent, your tenant must make a formal written request. This usually includes details of the proposed undertenant or assignee, their business, and the key terms of the transaction. You may ask for further information if it is reasonably required to assess the request.
Consent Must Not Be Unreasonably Withheld
Under section 19(1) of the Landlord and Tenant Act 1927, any clause requiring your consent is treated as including a condition that you must not unreasonably withhold it. The Landlord and Tenant Act 1988 adds duties to act within a reasonable time and to give written reasons for any refusal. The burden of proving reasonableness rests with you.
Delay, Silence, or Refusal
Delay, silence, or refusal without explanation may breach your statutory duties. A structured approach helps you comply with your obligations and demonstrate a professional, commercially aware response.
What Constitutes Unreasonable Withholding of Consent?
You withhold consent unreasonably if your refusal is based on reasons that do not relate to the lease, the property, or the proposed occupier. The courts assess your actual reasons at the time of the decision, and each case depends on its facts.
Case Law
Case law provides guidance:
- Ashworth Frazer Ltd v Gloucester City Council: refusal may be reasonable where the proposed occupier is likely to breach the lease.
- International Drilling Fluids Ltd v Louisville Investment: your reasons must relate to the landlord-and-tenant relationship and the subject matter of the lease.
- Bickel v Duke of Westminster: refusal based on personal preference or unrelated motives is unreasonable.
- Go West Ltd v Spigarolo: delay can itself amount to unreasonable withholding.
Unreasonable Refusal
Examples of unreasonable refusal include rejecting a financially reliable assignee without evidence of risk, objecting to a use that is clearly permitted by the lease, or demanding a premium without any contractual basis.
Reasonable Refusal
Refusal is more likely to be reasonable where the proposed occupier has weak financial standing, where the proposed use would cause practical difficulties for the building, or where your tenant has not provided the information you need to assess the request.
Conditions for Consent
You may impose conditions when giving consent for a commercial sublet agreement or property assignment, provided those conditions are reasonable and consistent with your lease. Any conditions must relate to the property, the proposed occupier, or the management of the building.
Common Conditions
Common conditions include requiring financial information, a guarantor, a rent deposit, or an authorised guarantee agreement. You may also require the underlease to mirror key terms of the headlease.
Section 19(1A) Conditions
For assignment clauses, section 19(1A) of the Landlord and Tenant Act 1927 may allow the lease to specify circumstances in which consent can be refused or conditions can be imposed. These provisions should still be applied carefully and consistently with the lease.
Information Requests
Any information you request must be relevant and proportionate. For example, you may reasonably ask for details of proposed works or evidence that the proposed use complies with planning and insurance requirements.
Prohibited Conditions
Conditions are likely to be prohibited if they require rewriting the lease, demand a premium without contractual basis, or impose discriminatory or unrelated requirements.
Licence to Assign or Underlet
A formal licence to assign or licence to underlet records your consent and any conditions, helping avoid disputes and providing a clear record of what has been agreed.
The Subletting Process
Subletting creates a two-tier structure. You remain in contract with the original tenant, while the undertenant occupies under a separate underlease. You need to ensure that the underlease is properly structured and does not increase risk.
Landlord and Tenant Relationship
Your original tenant remains fully liable under the headlease. If the undertenant defaults, you will look to the original tenant, who must then enforce the underlease.
Security Arrangements
Security arrangements require care. Rent deposits or guarantees under the underlease usually benefit the original tenant, not you. You may wish to ensure that the underlease is robust enough for the original tenant to manage default risk.
Due Diligence
A compliant subletting process involves checking your lease, receiving a formal request, assessing the proposed undertenant, and documenting consent in a licence to underlet. You should ensure that the underlease does not undermine the value or manageability of the headlease.
The underlease should also be shorter than the headlease so that a reversion remains with the head tenant. This helps preserve the headlease structure and avoids granting the undertenant an interest that extends beyond the tenant’s own leasehold term.
The Assignment Process
Assignment transfers your tenant’s entire interest in the lease to a new occupier. The assignee becomes directly responsible to you. You need to check suitability and ensure that any conditions protect the long-term management of the property.
Due Diligence
You will usually carry out due diligence, reviewing financial information, references, and the proposed use. You may also consider the impact on insurance, service charge arrangements, and the reliability of the rent stream.
Licence to Assign and Conditions
Your consent is documented in a licence to assign. Conditions may include an authorised guarantee agreement, a rent deposit, or confirmation that the assignee will comply with specific lease obligations.
Deed of Assignment
The deed of assignment transfers the lease to the assignee. For leases granted after 1 January 1996, the outgoing tenant is generally released from future liability unless an authorised guarantee agreement or another valid arrangement applies. The detailed position depends on the lease terms and the documents used for the assignment.
Landlord's Remedies for Unauthorised Subletting or Assignment
If your tenant sublets or assigns without consent, you may take action for breach of lease. Remedies can include seeking possession, requiring the breach to be remedied, or claiming damages. The appropriate remedy depends on the terms of your lease, the seriousness of the breach, and whether you have inadvertently waived your right to act.
Unauthorised Subletting or Assignment
Unauthorised subletting or assignment is a breach of the lease. Your remedies will depend on the wording of your lease and the nature of the breach. Many commercial leases include a forfeiture clause, allowing you to seek possession if your tenant parts with occupation or assigns without consent. Forfeiture is a significant step and must be exercised carefully, as the tenant or undertenant may apply for relief from forfeiture.
Notice of Forfeiture
Before taking action, you will usually need to serve a notice under section 146 of the Law of Property Act 1925. This notice must specify the breach and, in some cases, give your tenant an opportunity to remedy it. The court will consider the circumstances, including the seriousness of the breach and the conduct of both parties, when deciding whether to grant relief.
Damages
Damages may be available where you have suffered financial loss. This might include additional management costs, legal fees, or loss arising from a reduced rent compared with what could have been achieved with a permitted transaction. You may also seek an injunction requiring your tenant to bring the breach to an end, for example by removing an unauthorised undertenant.
Waiver
Waiver is an important consideration. If you accept rent from an unauthorised occupier or otherwise act in a way that recognises the continuation of the lease, you may lose the right to forfeit for that particular breach. Prompt action and clear communication help preserve your position.
Retrospective Consent
In some cases, retrospective consent may be more proportionate than immediate enforcement. This should be handled carefully, documented in writing, and considered alongside any waiver risk or continuing breach.
Structured Approach
A structured approach helps you respond effectively. This includes reviewing your lease, gathering evidence of the breach, considering whether forfeiture is proportionate, and taking advice before serving any formal notice. Careful handling reduces the risk of procedural errors and supports a commercially sound outcome.
Best Practices for Landlords
You can reduce risk and avoid disputes by approaching requests for a commercial sublet agreement or property assignment consistently. Clear lease drafting, prompt communication, proportionate due diligence, and accurate record-keeping all support legally robust decisions and help maintain the long-term value of your property.
Clear Approach to Requests for Subletting or Assignment
Requests for subletting or assignment are a normal part of managing commercial property. By adopting a clear and consistent approach, you are better placed to protect your interests and avoid unnecessary disputes.
Well-Drafted Lease
A well-drafted lease is the starting point. Clear alienation provisions help set expectations and reduce uncertainty when your tenant asks to sublet or assign. These provisions should address whether dealings are permitted, the conditions you may impose, and the information you are entitled to request.
Prompt Communication
Prompt communication is essential. Acknowledging your tenant’s request, identifying any further information needed, and responding within a reasonable time all help you comply with statutory duties and demonstrate a professional approach. Delay or silence can create avoidable risk.
Due Diligence
Proportionate due diligence supports informed decision-making. This may include reviewing the proposed occupier’s financial information, assessing the proposed use, and considering the impact on insurance, service charge arrangements, and the management of the building. The level of scrutiny should reflect the nature of your property and the terms of your lease.
Record-Keeping
Accurate record-keeping is important. Keeping a clear record of the information provided, the reasons for your decision, and the terms of any consent helps reduce the risk of challenge and provides a useful reference for future dealings. Using a formal licence to assign or licence to underlet ensures that conditions are properly documented.
Consistent Approach
A consistent approach helps you manage risk, maintain the value of your property, and support constructive relationships with your tenants. It also ensures that your decisions are aligned with the lease, statutory duties, and the long-term management of the building.
Understand your Lease Agreement
Subletting and assignment allow your tenant to deal with their lease, but both require careful handling. You must follow the terms of your lease, comply with statutory duties, and make decisions based on clear, property-related reasons. A consistent and well-documented approach helps protect the value of your property and reduces the risk of disputes.
When faced with a significant request for a commercial sublet agreement or property assignment, or with potential unauthorised dealings, it is sensible to seek legal advice. Early advice can help ensure that your decisions are legally robust and commercially sound.
Witan’s commercial property disputes solicitors can review your lease, assess the risks, and guide you through the process. You can contact us through our enquiry form or by calling 0300 303 2071.
