Rent Reviews in Commercial Leases: A CRE Broker's Guide

Rent reviews are one of the most misunderstood provisions in a commercial lease — and one of the most consequential. A poorly managed review can leave a landlord accepting below-market rent for the remainder of a term, or trap a tenant in a ratchet clause they did not notice when they signed.

For a CRE broker advising on commercial lettings, understanding the rent review mechanism is not optional. It shapes how you pitch a property, how you structure heads of terms, and how you support clients when a review falls due.

Types of rent review in UK commercial leases

Open market rent review — the most common type in institutional leases. The rent is adjusted to reflect what the premises could be let for on the open market at the review date, on the assumptions written into the lease (typically a willing landlord, willing tenant, vacant premises, and a new lease on the same terms). The comparable evidence gathered by chartered surveyors drives the outcome.

Upward-only rent review — a clause specifying that the reviewed rent can only increase or remain the same, never fall. Upward-only reviews were standard in institutional leases from the 1970s through the 2000s. They are now less common in new leases but still prevalent in existing ones. If your client is a tenant taking an assignment of a lease with an upward-only clause, this materially affects their risk profile.

RPI/CPI indexation — rather than an open market review, some leases tie the rent to the Retail Price Index or Consumer Price Index, subject to a cap and collar. Simpler to administer, but potentially more expensive in a high-inflation environment. Tenants who welcomed RPI caps in 2020 found them biting by 2023.

Turnover rent — the rent is linked to the tenant's trading turnover, common in retail parks and shopping centres. These require the landlord to audit tenant accounts and create a more complex ongoing relationship.

Fixed increases — some short leases (typically under ten years) build in fixed percentage increases at agreed intervals. Straightforward but inflexible.

The trigger date problem

Every open market rent review has a trigger date — the date from which the new rent is payable. In most leases, either party can activate the review by serving a trigger notice. If no one serves a trigger notice, the review does not simply lapse — under most modern leases, time is not of the essence for rent reviews, meaning the landlord can serve a trigger notice years late and claim back rent from the original trigger date.

This is a common source of disputes. A tenant who has been paying the same rent for three years assumes the review was missed. The landlord then serves a notice and claims a substantial backdated increase.

For brokers advising landlord clients: calendar every rent review trigger date and ensure notices are served correctly and promptly.

For brokers advising tenant clients: check whether a review has been triggered or waived, particularly on assignment.

Where AI adds value

Lease parsing — AI can read a commercial lease and extract the rent review mechanism, trigger dates, review assumptions, and any unusual provisions (cap and collar, upward-only clause, turnover element). This typically takes 5–10 minutes versus 45–60 minutes for manual extraction.

Comparable analysis — AI cannot replace a RICS-qualified surveyor's comparable evidence, but it can assist with:

• Summarising publicly available comparable transactions
• Identifying which comparables are most relevant based on the review assumptions in the lease
• Flagging market trends from accessible sources

Draft counter-notices — where the lease requires a formal counter-notice within a time limit, AI can produce a draft for solicitor review. Missing a counter-notice deadline can have serious consequences under certain lease provisions.

Heads of terms review — when acting on a new letting, AI can identify rent review provisions in draft heads of terms that carry commercial risk for your client, before the lease is engrossed.

Where surveyors remain essential

The open market rent determination — selecting comparables, adjusting for differences, applying lease assumptions, negotiating or referring to RICS arbitration or independent expert — requires a RICS-qualified surveyor with current market knowledge. This is a regulated area.

For upward-only reviews where the open market evidence suggests a rent reduction, the surveyor's skill is in demonstrating that the reviewed rent should remain at the existing passing rent rather than increase — a nuanced task requiring local market expertise.

Practical checklist for CRE brokers

Before completing a letting or assignment, confirm:

• What is the rent review mechanism and frequency?
• Is there an upward-only clause?
• Are there assumptions in the review that could produce an unrealistic result?
• What are the trigger dates and notice requirements?
• Who is responsible for serving trigger notices — landlord, tenant, or either?
• Is there a cap or collar on any RPI/CPI review?
• For assignments: has the existing review been triggered? Is there any backlog?

Running a lease through AI before heads of terms takes minutes and surfaces these issues before your client is committed.