Section 13 Rent Increases: The 2026 Form 4A Landlord Guide

Two days into the new regime and the inbox question for every UK landlord is the same. How do I actually put the rent up now? The answer, from 1 May 2026, is Section 13 of the Housing Act 1988 and the prescribed Form 4A. Nothing else. Rent review clauses in old tenancy agreements stopped working on Friday. Mutually agreed increases by side letter are still legal but unenforceable if the tenant changes their mind. And if you get the Section 13 process wrong, the notice is void, the rent stays where it was, and you wait twelve months before you can try again. This is the playbook for getting it right first time.

Five numbers to anchor the analysis. Twelve months is the minimum gap between rent increases under the new rules. Two months is the notice period a Form 4A must give before the new rent takes effect. £47 is what a tenant pays the First-tier Tribunal to challenge your proposed increase. Sixty days is roughly how long a contested increase sits at the tribunal before a decision lands. And zero is the amount the tribunal can now add above your proposed rent, a 2025 amendment that flipped the strategic calculation for landlords overnight.

What changed on 1 May, in plain English

Every assured shorthold tenancy and assured tenancy in England converted automatically into an assured periodic tenancy at one minute past midnight on Friday. Fixed terms ended. Any rent review clause inside the old contract became unenforceable. The Housing Act 1988 was amended so that the only valid mechanism to raise rent on these tenancies is a statutory Section 13 notice served on the prescribed Form 4A.

This matters because most pre-2026 tenancy agreements contained a rent review clause that allowed annual increases by formula, often CPI plus 1% or RPI plus 2%. Those clauses are now legally inert for any tenancy that converted on 1 May. Sending a tenant a contractual rent review letter referring to the old clause is not just ineffective, it could be treated as an attempt to bypass the statutory regime and trigger a council enforcement action. Read our Section 21 abolition guide for how the wider possession regime now interacts with rent disputes.

The Form 4A process, step by step

Form 4A is the prescribed notice published by gov.uk and updated for the May 2026 rules. Use it as a Word or PDF download from the official Ministry of Housing, Communities and Local Government page. Do not retype it from a letting agent template. The notice must include four things: the landlord's full name and address, the tenant's full name and the property address, the new rent amount and the date it takes effect, and a statement of the tenant's right to apply to the First-tier Tribunal.

The new rent date must fall at least two months after the notice is served. Service rules follow the contract or, where the contract is silent, the Section 196 of the Law of Property Act 1925: by hand, by first-class post to the tenant's last known address, or, if the tenancy agreement permits, by email. Recorded delivery with a Royal Mail tracking receipt is the gold standard. Posting alone leaves you arguing about whether the tenant received it if a dispute starts.

Twelve months from the last increase is the minimum interval. If the tenant moved in on 15 March 2026 paying £1,200, the earliest a Section 13 increase can take effect is 15 March 2027. If the tenancy began in 2023 and rent was last increased on 1 September 2025 by mutual agreement, your earliest effective date is 1 September 2026. Get the date wrong and the entire notice is void. The tribunal cannot patch it.

How to set the number without losing at tribunal

The tribunal applies a single test. Is the proposed rent the open market rent for a comparable property let on the same terms? If yes, the proposed rent stands. If no, the tribunal substitutes the market figure, but only downward. This is the change that landlords keep missing. Under the old rules, a tribunal could set rent at any market level, including above what the landlord proposed. Since the December 2025 amendment, your Form 4A figure is a strict ceiling. A tenant has effectively no downside risk to challenging beyond the £47 fee.

The practical implication is that you cannot punt a high number and hope the tribunal trims it back. Set the rent at genuine market level, evidenced, or accept that any number above market is a free hit for the tenant. Three sources of evidence carry weight at tribunal: Rightmove and Zoopla advertised lets in the same postcode for the same property type within the last 90 days, completed lets reported by the Office for National Statistics' Index of Private Housing Rental Prices, and comparable rents from your own portfolio if applicable. Print everything, date everything, and bring it to the hearing.

A reasonable rule of thumb in early 2026: across England, rents on new tenancies grew 3.4% in the year to March 2026 according to the ONS, with significant regional spread. Manchester and Birmingham new-let growth ran near 5%. Inner London and the South West tracked closer to 1.5%. If your proposed increase materially exceeds the local growth rate, you need direct comparable evidence, not just an index. Our rental demand analysis covers the regional split in more detail.

What happens when a tenant challenges

The tenant has until the day before the new rent takes effect to apply to the First-tier Tribunal (Property Chamber) using Form 6. A challenge filed after the effective date is invalid; the new rent stands. A challenge filed in time pauses the increase automatically. The tenant continues paying the existing rent while the tribunal considers the case.

Tribunal hearings typically run six to ten weeks from application to decision in 2026, depending on regional caseload. London and the South East have the longest queues post-1 May, with regions reporting 12-week waits as challenges piled in during the Act's transition period. The hearing is usually paper-based for straightforward rent disputes, sometimes with a property inspection. Either party can request an oral hearing, but most landlords find the paper process faster and cheaper.

Three outcomes are possible. The tribunal confirms the proposed rent and it takes effect from a date the tribunal sets, normally the original effective date. The tribunal sets a lower figure, which becomes the new rent from the same date. Or the tribunal finds the notice was procedurally defective and rules the increase invalid, meaning you start the twelve-month clock again from the date of the original increase you were trying to replace.

The mistakes that void a Section 13 notice

Procedural defects kill more rent increases than tribunal decisions on quantum. The five most common errors landlords make in the first weeks of the new regime, based on the early case reports surfacing in landlord forums this week:

Wrong form. Using a Form 4 from the pre-2026 era instead of Form 4A is fatal. The forms look almost identical but the statutory references differ. Download the current Form 4A from gov.uk every time you serve a notice; the form is updated periodically and using a stale version is a void-able defect.

Less than two months' notice. The notice period is calculated as a clear two months from the date of service, not from the date the notice was signed. If you posted it on 5 May, the earliest effective date is 5 July. Counting from the wrong starting point is the most common landlord error.

Twelve-month rule breach. Where the last rent change occurred under a mutually agreed deed of variation, the twelve-month clock still runs from that date, not from the start of the original tenancy. Any rent change in the prior twelve months blocks a Section 13 notice taking effect.

Effective date on the wrong day. The new rent must take effect on a day that aligns with the rental period. For a tenancy with rent paid on the 15th of the month, the new rent must start on the 15th, not the 1st. Misaligned dates void the notice.

Service to the wrong address. A tenant who notified you of a forwarding address, or a tenant who has multiple service addresses in the agreement, must receive the notice at the contractually correct address. Service to the property only, when the contract permits service to a different address, can be challenged.

Where AI tools save real time, and where they do not

The Form 4A process is repetitive, date-sensitive, and unforgiving of small errors. That makes it a good fit for AI assistance on the mechanical side: drafting the notice text from your tenancy data, calculating the earliest valid effective date, generating the comparable-rent evidence pack from postcode-level Rightmove and Zoopla data, and producing a service log with timestamps. A portfolio growth planner with rent review functionality can pre-stage notices across a portfolio so you serve in the right order on the right dates.

Where AI cannot help: the judgment call on whether to push a contested number, the property-specific reasoning on why your unit deserves a premium over a postcode median, and the strategic decision about whether a particular tenant is worth the relationship cost of a tribunal challenge. Those remain human calls, informed by data the AI can compile but not weighted by the soft factors only a landlord knows. The same logic applies to tenant screening at the start of a tenancy: AI structures the data, you decide what it means.

Read our rent in advance ban guide for the parallel changes affecting tenant onboarding from the same 1 May date. The two reforms work in tandem. Stronger upfront screening reduces the chance you ever need a contested rent increase, because the tenants you select are the ones who can absorb a market-rate review without dispute.

One closing thought. The tribunal ceiling rule has changed the strategic posture. The old game was to propose ambitiously and let the tribunal find a number. The new game is to set rent at evidenced market level, document it cleanly, and treat the Form 4A as a near-administrative exercise. Landlords who carry that mindset into the next twelve months will see fewer challenges, fewer void months, and tenants who renew rather than churn. The Act has not made rent increases impossible. It has made them disciplined.