Form 4A Explained: Serving a Rent Increase Notice in 2026

Since 1 May 2026 there is exactly one lawful way to increase the rent on a private assured tenancy: a Section 13 notice, served on the prescribed form — Form 4A. Get the form, the dates, or the service wrong and the increase simply never takes effect. Here's the whole process, start to finish.

What Form 4A Is — and Why It's Now the Only Route

Form 4A's full title is “Landlord's notice proposing a new rent for assured tenancies in the private rented sector”. It is the prescribed form for a rent increase under Section 13 of the Housing Act 1988, and it survived the Renters' Rights Act intact: the government confirmed the same form continues to apply to private tenancies after 1 May 2026.

What changed is everything around it. Because every assured tenancy is now periodic, and because the Act made contractual rent review clauses unenforceable, the informal routes landlords used for decades — a clause in the agreement, a letter proposing a new figure, a verbal agreement at renewal — are gone. If you want more rent, you serve Form 4A. If you didn't serve Form 4A, the old rent stands, whatever your tenancy agreement says.

The Three Rules Before You Fill Anything In

Once per 12 months. The new rent cannot start earlier than a year since the rent last changed — or since the tenancy began, if you've never increased it.

Two months' minimum notice. The date you put in the form for the new rent to start must be at least two months after the tenant receives the notice. Build in a few days' margin for service.

Market rate, not wish rate. The figure you propose should be defensible against comparable local lettings, because your tenant can send it to the First-tier Tribunal — and the Tribunal sets what it judges the market rent to be.

Filling In Form 4A, Section by Section

The form itself is short. The details that matter:

The parties and the property. Use the exact names on the tenancy agreement and the full property address. A notice addressed to the wrong entity — one joint tenant out of two, a misspelled company name — is an invitation to challenge.

The existing rent and the proposed rent. State both, with the payment period (weekly, monthly). If anything else is bundled into the payment — council tax, utilities, services — the form asks you to break it out.

The start date for the new rent. This is where notices fail. The date must be at least two months after service and at least 12 months after the last increase, and it must be the first day of a period of the tenancy. If your tenancy runs monthly from the 15th, the new rent starts on a 15th.

Date and sign it. Undated notices create exactly the ambiguity a tribunal challenge feeds on.

Serving the Notice — Where Increases Actually Fail

A perfectly completed Form 4A is worthless if you can't show the tenant received it. The two months run from receipt, not from posting — so “I put it in the post at some point in March” is not a date a tribunal can work with. Serve it in a way that creates evidence: follow whatever service method your tenancy agreement specifies, and keep a dated record of what was sent, to whom, and when it arrived.

This is the same discipline the rest of your compliance paperwork needs — and the same failure mode. If you can't prove service, the safest legal assumption is that it never happened. Our guide to proving you served a notice covers the options in detail.

After Service: the Three Outcomes

The tenant accepts — usually by simply paying the new rent from the start date. Nothing more is needed.

The tenant negotiates. You can agree a lower figure than the notice proposed. Put the agreed rent in writing, keep it with the tenancy file, and the 12-month clock runs from the change.

The tenant refers it to the First-tier Tribunal before the start date. The Tribunal determines the market rent: it can confirm your figure or reduce it, but never increase it beyond what you proposed. Until it decides, the existing rent continues. Your best protection is the homework you did before serving — comparable listings, condition of the property, what similar lets in the area actually achieve.

The Mistakes That Void a Form 4A Notice

Using an out-of-date version of the form. Serving within 12 months of the last increase. Giving less than two months' notice. A start date that isn't the first day of a tenancy period. Wrong names, wrong address, no date, no signature. And the most common of all: no evidence of service. Each one sends you back to the start of the process — which, with a two-month notice period, means a failed notice costs you a minimum of two months' worth of the increase.

Before you serve, run your dates through our rent increase calculator — it works out the earliest date the new rent can take effect and the latest date you can serve to hit it. And if you want the wider context on the 2026 rules, our full guide to the new rent increase rules covers the strategy; this page covers the form.

One habit ties it all together: keep the completed form, the service evidence, and any tenant response in the property's file, dated. If the increase is ever challenged — next month or in three years — the landlord who wins is the one who can produce the paper trail.

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