What is “comparable” evidence in rent increase cases?

WHAT IS “COMPARABLE” EVIDENCE IN RENT INCREASE CASES?

Since 1 May 2026, Section 13 Housing Act 1988 (as amended by section 6 of the Renters' Rights Act 2025) is the only lawful way to increase rent on an assured periodic tenancy in England. Rent review clauses and informal agreements no longer have effect.

I’ve been asked so many times about my thoughts on this, that I eventually decided to write about the practical aspects of rent increases, starting and finishing with “comparable” evidence. This comprises 100% of my thoughts and opinions as I am yet to read a tribunal decision on rent increases since the Renters’ Rights Act came into effect.

What is the tribunal looking to decide?

When a Section 13 rent increase is challenged, the First-tier Tribunal's task under section 14 is to determine the rent at which the property might reasonably be expected to be let in the open market by a willing landlord, on a tenancy with the same periods and terms. It is a valuation exercise, not a fairness contest: the tribunal is not asking what the tenant can afford or what the landlord would like, but what the market would pay for this property today. Tribunal panels can bring their own expertise and local knowledge, but the party who puts the better evidence of that market in front of them starts a long way ahead.

The statute also tells the tribunal to disregard certain things. Any premium or discount attributable to the tenant being a sitting tenant is ignored. Improvements the tenant carried out voluntarily are ignored, so a tenant cannot have their rent raised on the back of their own new kitchen. Any reduction in value caused by the tenant's failure to comply with the tenancy is also ignored. Disrepair that is the landlord's responsibility is not disregarded, however: a property with a leaking roof or failing damp proofing commands less on the open market, and a tenant is entitled to evidence exactly.

What makes a letting genuinely comparable?

The same micro market. The same street, estate or immediate neighbourhood, not merely the same postcode district. Rents can differ noticeably between one side of a railway line and the other, or between a road of period conversions and a road of new builds.

The same kind of property. Match the type (flat, terrace, semi), the number of bedrooms, and where possible the approximate size, floor level, outside space and parking. A two bedroom garden flat is not a comparable for a two bedroom sixth floor flat without adjustment.

The same condition and offering. Furnished against furnished, recently refurbished against dated, bills included against bills excluded. Where the comparable is better or worse than the subject property, it might be a good idea to say so and adjust, rather than hoping the tribunal will not notice.

The same moment in time. 

The tribunal is valuing the rent at the effective date, so evidence from the last three months or so is likely to carry far more weight than listings from a year ago. If a market is moving at three to four per cent a year, stale evidence would be the wrong evidence to seek to rely on.

Achieved rents over asking rents. 

What a property actually let for outranks what it was advertised at. England has no public register of achieved rents, so in practice the strongest portal evidence is a listing marked let agreed, ideally with a short time on the market, which shows the asking figure was close to what the market accepted. A property still advertised after eight weeks proves the opposite of what its asking price claims.

Where to find it

The portals. Rightmove, Zoopla, OnTheMove and OpenRent for example, are the primary sources for whole properties, and SpareRoom for rooms and HMOs. Search the immediate area, filter to the right property type and bedroom count, and capture both current listings and those marked let agreed. Both sides should probably take dated screenshots at the time, because listings disappear once a tenancy completes and cannot easily be recovered later.

Lettings agents. A short written market appraisal from one or two local agents, stating the rent they would expect to achieve for the subject property, should also be persuasive precisely because agents price to let, not to flatter. Landlords can use these to support a proposed figure; tenants can equally ask an agent what a property in its actual condition would fetch.

Official statistics. The ONS Price Index of Private Rents publishes average private rents by local authority area and bedroom count, and became a full official statistic in May 2026. It is context rather than proof, because an average across a borough cannot capture one street, but it usefully frames whether a proposed figure sits within or well outside the local norm. Local Housing Allowance rates offer similar background context only, since they are set at the cheaper end of the local market rather than at its middle.

Your own records. A landlord with similar units can put in their own recently agreed tenancies as achieved rent evidence, which is exactly what it claims to be. A tenant's own tenancy history, including what the property let for and when, might also help the tribunal see the trajectory.

How to present it

In my opinion, quality should always beat volume. Three to six strong comparables, set out in a simple schedule showing the address or location, a brief description, the rent, whether it was asking or achieved, the date, and the source, should do more work than twenty screenshots in no order. 

Add a short paragraph of honest commentary on each: how it compares to the subject property and what adjustment, up or down, that suggests. Photographs of the subject property's actual condition, dated, belong alongside it, particularly where condition is the tenant's central point. Most rent determinations are likely to be decided on the papers, so the bundle has to speak entirely for itself.

The mistakes that can lose a case (imo)

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1.  Cherry picking the single cheapest or dearest listing in the area and presenting it as typical. 
2.  Relying on asking prices as though they were achieved rents. 
3.  Using evidence from the wrong season or the wrong year. 
4.  Comparing across property types without adjustment. 
5.  Ignoring the subject property's condition, in either direction. 
6.  On the landlord side, proposing a figure first and hunting for evidence afterwards.

This paper states the law of England as at July 2026 and is for general information only; it is not legal advice.