Open market rent is the rent at which a property "might reasonably be expected to be let in the open market by a willing landlord". It is the statutory benchmark for rent increases in England. The landlord proposes the figure on the Form 4A notice, and if the tenant refers it, the First-tier Tribunal decides.
Open market rent is the rent a property would achieve if newly let on the open market today.[1][3] It is the benchmark for every rent increase on a private assured tenancy in England: the landlord proposes the figure, and the First-tier Tribunal decides it if the tenant refers the notice.[4][8] For the wider process, see our complete guide to rent reviews.
Where does the definition come from?
Section 14 of the Housing Act 1988, as amended by the Renters' Rights Act 2025. When a rent is referred, the tribunal decides the figure at which the property "might reasonably be expected to be let in the open market by a willing landlord" on equivalent terms.[1] Government guidance puts it more plainly: "the price that would be achieved if the property was newly advertised to let".[2]
Since 1 May 2026 every private assured tenancy in England is periodic, rent review clauses are of no effect, and the only lawful route to an increase is a Section 13 notice on the prescribed Form 4A.[5][4][2] This applies in England only; Wales and Scotland have separate regimes.
Who decides the open market rent?
The landlord first, the tribunal last. In practice you research the figure and serve the notice on the landlord's behalf; if the tenant accepts, the proposed rent simply takes effect from the start date.[4]
Form 4A then gives the tenant three options: accept and pay from the start date; agree with the landlord to vary what the notice proposed, to a rent lower than the figure on it, no change at all, or a later start date, never higher, recording the agreement in writing or the rent on the notice takes effect regardless; or refer the notice to the First-tier Tribunal (Property Chamber).[6] A referral costs £47 and must reach the tribunal before the new rent's start date.[7]
A referred rent is decided within two limits. If the open market rent is lower than the proposal, the tribunal sets that. Otherwise it sets the proposed rent. It can never go above the notice figure.[8] The increase is not backdated either. If the decision lands after the start date, the new rent runs from the first rent period on or after that decision, and the old rent stays payable until then.[8][6] See what happens at a tribunal challenge for the full sequence.
What does the tribunal take into account?
The property as it stands, let on equivalent terms. Form 4A tells tenants "the tribunal can consider other factors like the condition of the property".[6] The statute disregards value added by the tenant's own improvements and value lost through the tenant's failure to comply with the tenancy.[1]
Beyond that, evidence decides it. Tenants preparing a referral are told to gather "evidence from similar nearby properties (similar size, features and location)".[7] The same discipline serves your side. See what evidence supports a rent increase.
Is there a cap on how much rent can rise?
No. The Act sets no percentage cap and no index link; government guidance says rent can rise "once per year to the market rate".[2] The controls are procedural: at least two months' notice, one increase every 52 weeks (53 where the anti-drift rule applies), and the tenant's right to refer.[4]
A tenant has little to lose by referring an ambitious figure. The outcome cannot exceed the proposal, and the old rent stays payable while they wait.[8][6] So a realistic, evidenced figure is more likely to be accepted, and to hold if it is tested.
Is open market rent the same as the ONS average?
No. The ONS Price Index of Private Rents (PIPR) tracks average rents across the whole rented stock, sitting tenants included, at local-authority level in England. It is a mix-adjusted average, not a valuation of any one property.[9] For context, England's average private rent was £1,451 a month in July 2026, up 3.8% over the previous 12 months (ONS, August 2026 release).[10]
| Open market rent | ONS index (PIPR) | |
|---|---|---|
| What it describes | One property: what it would let for if newly advertised[1] | Average rents across a local authority's rented stock[9] |
| How it is set | Landlord's proposal; tribunal decision if referred[8] | Mix-adjusted model of achieved rents, published monthly[9] |
| Role in a review | The statutory benchmark | Context for average local movement |
Index data shows how average local rents have moved since the rent was last set. Our Free Rent Indexation Tool generates that reference point from published ONS data, a starting point rather than a market rent determination, and our PIPR explainer covers the method. Comparables answer the statutory question itself: what would this property let for? For the notice that carries your figure, see what is a Section 13 notice.
This article is general information for letting agents in England, not legal advice.
Sources
- Housing Act 1988, section 14 (determination of rent by tribunal), as amended
- MHCLG, Guide to the Renters' Rights Act
- GOV.UK, Assured periodic tenancies: a guide for landlords — rent increases
- Housing Act 1988, section 13 (increases of rent under assured tenancies), as amended
- The Renters' Rights Act 2025 (Commencement No. 2 and Transitional and Saving Provisions) Regulations 2026 (SI 2026/421)
- Form 4A, landlord's notice proposing a new rent (GOV.UK, version 05.26)
- GOV.UK, Apply for an open market rent determination
- Renters' Rights Act 2025, section 7 (inserting sections 14ZA and 14ZB, Housing Act 1988)
- ONS, Price Index of Private Rents QMI (quality and methodology information)
- ONS, Private rent and house prices, UK (latest monthly bulletin)