How a Form 4A Rent-Increase Notice Becomes Invalid

Since the Renters' Rights Act 2025 came into force, there is only one lawful way to raise the rent on an assured tenancy: the statutory section 13 procedure, using the prescribed Form 4A. Rent-review clauses and quiet "let's agree a new figure" arrangements no longer do the job. And section 13(4A) of the Housing Act 1988 says the rent "may not be greater than the rent for the previous period except by virtue of" a notice under section 13 (or an agreement following one), a tribunal determination under section 14, or a written agreement following such a determination — so the notice's dates carry the whole increase.

Most landlords know they need to give notice. Far fewer know the detail that catches landlords out — the effective date. This guide leads with that trap, then covers the notice period, the 52-week interval between increases, and the tribunal safeguard.

Disclaimer: This guide is for information only and does not constitute legal advice. Always work from the current prescribed form and check the position for your tenancy.

The Trap Landlords Miss: The Effective Date

Start here, because this is the one landlords miss. Section 13 of the Housing Act 1988 — the section the Form 4A operates under — requires the notice to propose "a new rent to take effect at the beginning of a new period of the tenancy specified in the notice."

In plain English: the date the new rent starts must line up with the start of a rental period, not a date you find convenient. If the rent runs monthly from the 5th, the new rent must begin on the 5th — not the 1st, not the 20th. A mid-period date is not the beginning of a new period of the tenancy, however much notice you gave and however reasonable the increase is.

There is a second timing rule buried in the same section: the first increase cannot take effect until the date 52 weeks after the date on which the first period of the tenancy began. So the effective date has to satisfy two conditions at once — it must fall at the start of a tenancy period, and it must be far enough into the tenancy. Miss either and the date is not one section 13(2) allows.

The Notice Period: At Least Two Months

The Form 4A must give the tenant at least 2 months' notice before the new rent takes effect. Two months is the floor, not a target — count generously and align the end of that period with the start of a tenancy period, per the trap above. A date less than two months after the notice is served is not one section 13(2) allows.

Use the current prescribed form. The government publishes it in the assured tenancy forms collection; a saved copy from before the reforms may be the wrong version. Our checklist on the section 13 rent-increase notice walks through completing it correctly.

Get the date before you serve. Our free Rent Increase Date Checker gives the earliest date your new rent can start and the rule that sets it — two months' notice, 52 weeks between increases, or the start of a rent period. It works out dates only; it does not produce or check a notice.

52 Weeks Between Increases, Not Twelve Months

Two more rules bound when you can act at all:

• The first increase. It cannot take effect earlier than 52 weeks after the date on which the first period of the tenancy began — the rule above.
• Every later increase. It cannot take effect earlier than 52 weeks (or, in the case set out in section 13(3B) of the Housing Act 1988, 53 weeks) after the date on which the last increase took effect. A Form 4A that proposes an earlier date is not one section 13(2) allows.

These are not stylistic preferences; they are the dates section 13(2) sets. Fold them into your wider tenancy management so a well-meaning early rise does not turn into an unlawful one.

The Tribunal Safeguard: It Cannot Go Higher Than You Asked

If the tenant thinks the proposed rent is above the market, they can refer the Form 4A to the First-tier Tribunal (Property Chamber). The important change under the new regime is the direction the risk runs: the tribunal cannot set a rent higher than the figure you proposed in your notice.

Under the old rules a challenge could, in principle, result in a higher assessed rent — which discouraged tenants from ever challenging. Now the proposed figure is effectively a ceiling for that review: the tenant never pays more than you asked for. Two practical consequences for landlords:

• Propose a figure you can justify as market rent. An inflated ask is more likely to be challenged, and the tribunal review only ever moves the number down or leaves it, never up.
• Keep evidence of comparable local rents with the notice, so that if it is referred, you can support the figure. What the tribunal weighs, and how section 14ZB sets the new rent, is in how to evidence a market rent increase for the Tribunal. You can read more about the tribunal route on the First-tier Tribunal (Property Chamber) page.

Other Mistakes to Check Before You Serve

GOV.UK's guidance for tenants says: "Your landlord must send you a valid section 13 notice before increasing your rent." A tenant can ask the tribunal to decide whether the notice is valid, on the paper MR1 form (GOV.UK: apply for a market rent determination). Besides the dates above, the same guidance says a valid notice must "include your correct details, such as your name and address" and "be on the correct form and signed by the landlord".

The wrong form, or an old Form 4. Section 13(2) requires "a notice in the prescribed form". For a private assured tenancy the prescribed form is Form 4A, "or a form substantially to the like effect" (regulation 3(1)(d) of the 2026 Prescribed Forms Regulations). The 2015 Regulations that prescribed the old Form 4 were revoked "in relation to any private assured tenancy" on 1 May 2026. The current Form 4A is version 05.26 on GOV.UK, last updated 1 May 2026.

Serving it a way the agreement does not allow. Form 4A's own note to landlords says: "You need to be able to evidence that you served the notice on your tenant. If your written tenancy agreement specifies agreed methods of service, use one of those. If it does not you can serve it by handing it over to your tenant in person, leaving it at the tenant's address or sending it by registered post." So email is a way to serve it only if your written tenancy agreement sets out email as an agreed method.

Forgetting the 53rd week. For a later increase, Form 4A's Note A3 adds that the new rent date "cannot be more than 6 days before the anniversary of the date given in question 4.4. If it would be, the landlord must wait an extra week (53 weeks in total) before the increase can start." Question 4.4 asks for the date of the first rent increase after 11 February 2003.

A Quick Checklist Before You Serve

Before you serve a Form 4A, confirm every one of these:

1. It is the current prescribed Form 4A.
2. The effective date is the start of a tenancy period.
3. The effective date is at least 52 weeks after the tenancy's first period began (for a first increase).
4. You are giving at least 2 months' notice.
5. For a later increase, the effective date is at least 52 weeks after the last increase took effect (53 weeks in the s.13(3B) case).
6. The proposed rent is a defensible market figure you can evidence.

Points 1 to 5 come from section 13(2) and the prescribed form; point 6 is what the tribunal looks at if the tenant applies.

What's Actually in Force: The Rest of This Series

• Does Awaab's Law apply to private landlords?
• Section 8 Ground 8: why your rent-arrears notice can fail
• Rent increases under the Renters' Rights Act: how a Form 4A notice becomes invalid (this article)
• Pets and the Renters' Rights Act: the 28-day duty landlords keep missing

Frequently Asked Questions

How do I legally increase the rent under the Renters' Rights Act?

You use the statutory section 13 process: serve the prescribed Form 4A on the tenant giving at least 2 months' notice. The first increase cannot take effect earlier than 52 weeks after the date on which the first period of the tenancy began, and a later increase not earlier than 52 weeks (or, in the case set out in section 13(3B) of the Housing Act 1988, 53 weeks) after the date on which the last increase took effect. Informal agreements and rent-review clauses can no longer be used to force an increase — the Form 4A route is the mechanism.

Why would a Form 4A rent increase be invalid?

GOV.UK's guidance lists what a valid section 13 notice must do: give at least 2 months' notice, not increase the rent within 52 weeks of the last increase, start the increase on the correct date, include the tenant's correct details, and be on the correct form and signed by the landlord. The date is the trap: the new rent must start at the beginning of a new period of the tenancy, which section 13(2) requires — a date in the middle of a rental period is not one.

Can the tribunal set a higher rent than I asked for?

No. If the tenant challenges the increase at the First-tier Tribunal, the tribunal cannot set a rent higher than the amount you proposed in the Form 4A. That removes the old risk that a challenge could backfire against the tenant, and it means your proposed figure is effectively a ceiling for that review.

This guide is for information only and does not constitute legal advice.