Rent increase calculator for UK landlords from 2026

Increasing your tenant's rent in England is now governed entirely by the Renters' Rights Act 2025, which came into force on 1 May 2026. The process is simpler than it used to be in one sense, there is now only one legal route, but it carries stricter requirements than the old system. This guide explains how to calculate a fair rent increase, how to serve the correct notice, what tenants can do if they disagree, and how the new rules differ from what applied before.

How to calculate a rent increase UK

Enter your current monthly rent and either a proposed new amount or a percentage in the calculator above. The calculator will show your new monthly and annual rent, the pound increase per month, and the minimum notice date you need to serve to make the new rent effective on your chosen date.

For percentage increases, most UK landlords benchmarked against one of three reference points in 2025/26: the Office for National Statistics private rental index (showing annual rent growth of around 7% to 9% for much of 2024/25), the Consumer Prices Index (CPI, running at approximately 2–3% by early 2026), or simply local comparable rents on Rightmove and Zoopla. There is no statutory cap on rent increases in England — the requirement under the Renters' Rights Act is that the increase must be to the open market rent. A proposed increase that exceeds market rent can be challenged by the tenant at the First-tier Tribunal (Property Chamber).

How often can a landlord increase rent?

From 1 May 2026, landlords in England can increase the rent on an assured periodic tenancy only once in any 12-month period. This applies to all tenancies, there is no ability to use a contractual rent review clause, since all such clauses in existing agreements became void on 1 May 2026 and cannot be included in new agreements. The Section 13 procedure using Form 4A is the only legal route. If you attempt to increase rent more frequently than once every 12 months, or by any means other than a valid Form 4A notice, the increase has no legal effect.

How to increase rent under the Renters' Rights Act — Section 13 and Form 4A

Section 13 of the Housing Act 1988 is the statutory mechanism for increasing rent on an assured periodic tenancy. Under the Renters' Rights Act 2025, this process has been updated and now uses Form 4A (replacing the old Form 4). Form 4A is the "Landlord's notice proposing a new rent under an assured periodic tenancy", you can download the current version from GOV.UK.

To serve a valid Section 13 notice using Form 4A you must: give at least two months' notice before the proposed effective date of the new rent; ensure the new rent takes effect on the first day of a tenancy period (so for a monthly tenancy paid on the 1st, the new rent must start on the 1st of a month); propose a rent no higher than the open market rent for the property; and serve the notice correctly, by hand, first-class post, or email if the tenancy agreement permits email service.

The calculator above shows the minimum notice date based on your proposed effective date. If you serve on 15 April 2026 and want the new rent to start on 1 July 2026, the two-month requirement is met (15 April to 1 July is more than two months). If you want the new rent to start on 1 June 2026, you would need to serve by 1 April 2026 at the latest.

How much notice for a rent increase UK?

Under the Renters' Rights Act 2025, landlords must give at least two months' notice for any rent increase on an assured periodic tenancy. This increased from one month, which applied to most monthly tenancies under the old regime. The two-month minimum applies regardless of the tenancy payment frequency. For weekly tenancies, the notice must still be at least two months, not two weeks.

What is a fair rent increase UK?

There is no statutory cap on the amount of a rent increase in England, but the increase must be to the open market rent, meaning the rent a willing landlord would accept from a willing tenant on the open market at the time of the notice. A proposed increase above market rent can be challenged. As a practical benchmark:

ONS data showed private rents rising approximately 7–9% nationally in the year to early 2026, though this varies significantly by region, London and the South East saw higher increases, while some northern regions saw more moderate growth. CPI inflation in early 2026 was approximately 2–3%. Most landlords use a combination of local market comparables (from Rightmove, Zoopla, or local letting agents) and their own cost increases to justify the proposed figure.

If you are uncertain whether your proposed increase is at or below market rent, obtain two or three recent comparable lettings in the same area and property type before serving the notice. Keep that evidence, if the tenant challenges the increase at tribunal, you will need it.

Can a tenant challenge a rent increase UK?

Yes. Under the Renters' Rights Act 2025, a tenant who receives a Section 13 notice can refer the proposed rent to the First-tier Tribunal (Property Chamber) for a determination of the open market rent. The referral must be made before the effective date of the proposed new rent. If the tribunal sets a rent lower than you proposed, the tribunal's figure applies. Importantly, the tribunal can also set a rent lower than the current rent if the evidence supports it, though this is rare in practice.

The fact that tenants now have this right in all tenancies (rather than only in statutory periodic tenancies as previously) makes evidence of comparable market rents more important than ever before serving a Section 13 notice.

Rent increase in line with inflation UK — CPI and RPI

Before 1 May 2026, many landlords included contractual rent review clauses linking increases to CPI or RPI. All such clauses are now void. You cannot use a CPI or RPI-linked formula to increase rent, you must serve a Form 4A notice proposing a specific new rent figure, and that figure must represent the open market rent.

CPI and RPI remain useful as informal benchmarks when deciding what percentage increase to propose. If your current rent is materially below market rent because it was last increased several years ago, a single increase to catch up to market may be larger than recent inflation figures suggest. The calculator above lets you model any percentage increase and see the resulting annual cost, which you can compare against local market data.

Rent increase calculator UK — worked example

A landlord has a tenant paying £1,200 per month in Manchester. The tenancy is monthly, with rent due on the 1st of each month. The last rent increase was in April 2024, meaning by April 2026 the 12-month rule is satisfied and a new increase can be proposed.

The landlord researches local comparables and finds similar two-bedroom flats letting for £1,280–£1,320 per month. They decide to propose £1,275, a £75 per month increase (6.25%).

Entering these figures into the calculator above: new monthly rent £1,275, new annual rent £15,300, increase of £75 per month (£900 per year), percentage increase 6.25%.

The landlord wants the new rent to start on 1 July 2026. Working back two months, they must serve Form 4A by 1 May 2026 at the latest. They download the current Form 4A from GOV.UK, complete it with the current rent (£1,200), proposed new rent (£1,275), and effective date (1 July 2026), and serve it on the tenant by email on 28 April 2026, having confirmed the tenancy agreement permits email service.

The tenant has until 1 July 2026 to refer the matter to the First-tier Tribunal if they disagree. If they do not refer it, the new rent of £1,275 takes effect on 1 July 2026.

Section 13 notice 2026 — what has changed under the Renters' Rights Act

Before May 2026, landlords could increase rent by mutual agreement in writing, via a rent review clause in the tenancy agreement, or by serving a Section 13 notice using Form 4. From 1 May 2026:

Rent review clauses are void — they have no legal effect in existing or new assured periodic tenancies. Mutual agreement still works, if a tenant agrees in writing to a new rent, no Section 13 notice is required. Section 13 via Form 4A is now effectively the universal fallback for any increase the tenant does not agree to. Form 4 is replaced by Form 4A for all new notices. The notice period is now two months minimum for all assured periodic tenancies. The increase must be to open market rent, and tenants can challenge it at the First-tier Tribunal before the effective date.

For existing Section 13 notices served using Form 4 before 1 May 2026: if the notice was validly served before commencement, it remains effective under transitional provisions. Any new notice served from 1 May 2026 must use Form 4A.

For a broader guide to the Renters' Rights Act changes and how they affect your tenancy management, see the August Renters' Rights Act hub.

Also see: How to increase tenants' rent · How to set the right rent price · Section 13 dictionary entry · Rent payment term calculator · Rental income tax calculator · Periodic tenancy · Tenancy agreement template · Renters' Rights Act hub · How rental income is taxed in the UK · All calculators

Disclaimer

This calculator is for guidance only and does not constitute legal or professional advice. Rent increase rules changed on 1 May 2026 under the Renters' Rights Act 2025. Always serve the correct Form 4A notice and seek professional advice if you are unsure whether your proposed increase is enforceable. August accepts no liability for decisions made on the basis of this tool.