Expert Solicitors for Side Letters & Supplemental Agreements

A side letter is a separate document signed alongside a commercial lease that sets out additional terms, promises, or agreements between landlord and tenant that are not included in the main lease. Our solicitors often draft these to clarify specific obligations or provide assurances on matters like rent-free periods, fit-out contributions, or break clause conditions.

Side letters are generally personal agreements between the original parties and do not automatically run with the land. This means they may not bind successors in title, which can be a significant risk for tenants. Our commercial lease solicitors advise on protecting your interests, including whether to register certain side letters at the Land Registry or incorporate key terms into the lease itself.

While both documents address additional terms, the key difference lies in their legal effect. A side letter is typically a personal arrangement that may not bind future owners, whereas a supplemental agreement forms part of the formal lease documentation and is binding on all parties, including future landlords and tenants. Our solicitors help you choose the right document for your circumstances.

You should consider a supplemental agreement when the changes to your lease need to have permanent legal effect and bind future owners of the property. This is particularly important for variations affecting the value of the lease, security of tenure, or significant financial obligations. Our lease solicitors recommend supplemental agreements when dealing with matters that could affect future sales or refinances of the property.

Yes, side letters can significantly impact lease value, particularly if they contain rent concessions, fit-out contributions, or break clause rights. Investors and lenders often scrutinise side letters during due diligence, and their enforceability against future owners is a key consideration. Our solicitors ensure side letters are properly structured to protect or enhance your leasehold interest.

Our commercial lease solicitors negotiate side letter terms on behalf of landlords and tenants, ensuring the document accurately reflects the agreed position and provides appropriate protection. We advise on what terms to include, what risks to address, and how to structure the side letter to achieve your commercial objectives while minimising legal exposure.