Lettings trade body Propertymark says hard evidence, accurate property descriptions and a realistic assessment of a property’s condition are all required before a rent rise can be implemented.

The organisation says it’s examined a number of. First-tier Tribunal decisions made in August and September involving properties in Leeds, Manchester, Ashton-under-Lyne, and London. 

Each shows how the property’s market rental value was assessed and highlights why landlords need clear evidence to stop challenges by tenants succeeding.

In one case – in Manchester – a tribunal challenge actually ended with the rent being set below the amount already payable. 

Propertymark says far more evidence is required than many agents may expect. It comments: “Properties within the same building or immediate neighbourhood carried particular weight in Manchester and Ashton-under-Lyne. The London tribunal, meanwhile, found that the information supplied was insufficient for accurate comparisons.

“Agents should record relevant details such as floor area, layout, bathrooms, furnishings, condition and included services. 

“Clearly distinguish advertised rents from agreed rents: both featured in these decisions, but their usefulness depends on how closely the properties match and how much supporting detail is available.”

In another decision, referring to a London property, the landlord described the property as two bedrooms but the tribunal considered the flat’s size more consistent with a small one-bedroom property; it also identified the absence of a conventional lounge.

Propertymark adds in its warning to members: “When assessing rent, consider how the accommodation functions as a home. Floor area, room sizes, and usable living space can make properties with the same bedroom count materially different.

“The London tribunal had no evidence confirming that the agent who supplied a valuation had inspected the property. 

“This highlights the value of explaining how an assessment was reached, including whether an inspection took place, which comparisons were used and how condition affected the figure. An agent’s opinion should be supported by evidence that the tribunal can assess.”

Propertymark also advises agents to keep dated photographs, repair records and evidence of completed work. “Establish whether problems remain unresolved and whether repairs have restored the property’s use and condition” it adds.

And where landlords handle maintenance themselves, agents should still obtain the relevant records and check the chronology before presenting evidence or recommending a rent increase.

Here is one particularly interest case study, cited by Propertymark and where in fact the landlord’s evidence proved the most persuasive

The trade body says: “One of the first published decisions under the [Renters Rights Act] concerned a two-bedroom flat at Skylark Point, a build-to-rent development in London.

“The existing rent was £3,102.82 per month, and the landlord proposed increasing it to £3,180. The tenant argued that £3,040 was a more accurate market rent.

“Both parties submitted comparable evidence. 

“The tenant relied on four two-bedroom properties advertised by the same landlord in the immediate area,  whilst the landlord provided details of nine rents agreed for similar flats within Skylark Point and a neighbouring development between April and June 2026.

“The Tribunal gave greater weight to the landlord’s evidence because it showed rents that had actually been agreed, rather than asking prices. 

“As the proposed rent was below all nine of the landlord’s comparables, the Tribunal confirmed the increase to £3,180.

“The decision is not binding on other tribunals, and every case will depend on its own facts. However, it supports the UKJ government guidance which states that information from property portals can help, but evidence from completed rental agreements is stronger.”