For many commercial tenants, a lease that once suited the business can become a burden. Changes in trading conditions, growth, downsizing, or a move toward hybrid working often prompt tenants to seek ways to terminate a lease early or reduce ongoing costs. Two common options are to assign the lease or to sublet the premises. While these routes can be effective, both carry legal and financial risks that tenants should understand before proceeding.
This article explains the key differences between assignment and subletting, outlines the legal framework in England and Wales, and highlights the practical issues tenants should consider before taking action.
Assignment and Subletting: The Key Differences
Although assignment and subletting both involve transferring occupation of the premises, they operate in very different ways.
An assignment involves transferring the tenant’s entire interest in the lease to a new tenant, known as the assignee. The assignee steps into the tenant’s place and pays rent directly to the landlord. In theory, this is a permanent exit from the lease, although ongoing liability often remains.
A sublet occurs when a tenant grants a sublease to a third party while remaining the tenant under the original lease. The original tenant becomes the head tenant and is, in effect, a landlord to the subtenant. Rent from the subtenant is paid to the head tenant, who must continue paying rent to the landlord regardless of whether the subtenant pays.
The distinction matters because liability usually continues in different ways, particularly where authorised guarantee agreements or subtenant defaults are involved.
Landlord Consent and the Legal Framework
Most modern commercial leases restrict assignment and subletting without the landlord’s prior written consent. Where a lease contains no alienation provisions at all, a tenant may generally assign or sublet without needing consent. In practice, however, genuinely silent leases are now uncommon, and tenants should not assume freedom to transfer without first checking the lease terms carefully.
Under statute, a landlord must not unreasonably withhold consent where the lease allows assignment or subletting with consent. In addition, the landlord has a duty to process the tenant’s application within a reasonable time and to provide reasons if consent is refused.
There is no fixed statutory deadline for responding. What is reasonable depends on the circumstances, including the transaction’s complexity and whether the tenant has provided all relevant information. Delays often occur because applications are incomplete, which can significantly weaken a tenant’s position if a dispute arises.
What Information Landlords Typically Require
Landlords are entitled to satisfy themselves that the proposed assignee or subtenant is suitable. In practice, this usually involves detailed financial and commercial scrutiny.
Tenants should expect requests for:
- Recent accounts, often covering up to three years where available
- Bank or accountant references
- Details of the proposed use of the premises
- Business plans or trading forecasts for new ventures
- Information about guarantors or rent deposits
Failure to provide adequate information promptly is one of the most common reasons consent is delayed or refused.
Assignment and Ongoing Liability
A common misconception is that an assignment always results in a clean break for the outgoing tenant. For leases granted since 1996 (following the enactment of the Landlord and Tenant (Covenants) Act 1995), the statutory starting point is that an assigning tenant is released from future tenant covenants on a lawful assignment. In practice, however, landlords frequently require the outgoing tenant to enter into an authorised guarantee agreement, known as an AGA, as a condition of consent.
An AGA means the outgoing tenant guarantees the assignee’s performance of the lease, typically until the lease is next assigned. If the assignee defaults, the landlord can pursue the original tenant for the resulting losses.
In limited circumstances, tenants may be able to negotiate a full release from ongoing liability, usually where the assignee has a significantly stronger covenant. However, this remains the exception rather than the rule and should not be assumed when planning an exit from the lease.
Subletting and Continuing Responsibility
Subletting carries a different set of risks. The head tenant remains fully responsible to the landlord for all lease obligations, including rent, service charge, repairs, and compliance with user clauses.
If the subtenant fails to pay rent or breaches the sublease, the landlord will still look to the head tenant. The head tenant must then pursue the subtenant separately, often at additional cost and risk.
Tenants should also be aware that many leases prohibit subletting of part of the premises or permit subletting only of the whole premises. Partial subletting, such as one floor of a building, is often restricted and should not be assumed to be permitted.
Security of Tenure and Contracting Out
Where premises are sublet, landlords often insist that the sublease is excluded from the security of tenure provisions of the Landlord and Tenant Act 1954. This means the subtenant has no automatic right to renew the lease at the end of the term.
Contracting out must be carried out correctly and in accordance with the prescribed statutory process to be effective. If this is done improperly, the subtenant may acquire renewal rights unexpectedly, creating significant issues for both the landlord and the head tenant.
Costs and Professional Fees
Most leases require the tenant to pay the landlord’s reasonable legal and administrative costs associated with an application for consent. These costs are usually payable regardless of whether consent is ultimately granted, provided the lease permits this.
In practice, fees typically range from several hundred to several thousand pounds, plus VAT, depending on the transaction’s complexity and any required negotiations. Tenants should factor these costs in from the outset.
Market Considerations in 2026
While the legal framework has remained stable, commercial pressures continue to influence how assignment and subletting are used.
Subletting has become increasingly common as businesses seek to reduce surplus space. In some locations, tenants may even be able to sublet at a higher rent than they pay under their own lease. However, many leases restrict this by requiring any excess rent to be shared with the landlord or by prohibiting profit altogether.
Tenants should also be mindful that modern occupiers often have specific requirements around energy efficiency, building systems, and fit-out. These expectations can affect a space’s marketability and the likelihood of landlord consent.
Common Pitfalls to Watch For
Before proceeding, tenants should pay close attention to the following issues:
- Alienation clauses: These vary significantly between leases and often contain detailed conditions that must be satisfied.
- Rent arrears: Landlords can usually refuse consent if the principal rent or other sums are outstanding.
- Break clauses: Some break options are lost on assignment or only operate if the tenant remains in occupation.
- Forfeiture risk: If the headlease is forfeited, a sublease may fall away, leaving the subtenant without rights and the head tenant exposed to claims.
- Existing security: Guarantees and rent deposits often continue after assignment or subletting unless expressly released.
Getting It Right
Assigning or subletting a commercial lease can be an effective way to manage risk and reduce costs, but it is rarely straightforward. The detail of the lease, the quality of the incoming party, and the approach taken to landlord consent all play critical roles.
Tenants considering either option should review their lease carefully and take legal advice at an early stage. Doing so can help avoid delays, unexpected liabilities, and costly disputes and ensure the chosen route genuinely achieves the intended commercial outcome.
About the author
Brinda Granthrai joined RIAA Barker Gillette (UK)’s commercial real estate team in May 2025. She brings over 15 years of experience advising high-net-worth individuals, private companies and international investors on complex real estate transactions. She works closely with the team to deliver commercially focused, pragmatic solutions across the full property lifecycle.