A second Form 4A lands while your tribunal challenge is still undecided: the tenant walkthrough (RRA, 2026)

A renter does everything right. They get a Form 4A rent increase notice, they spot the procedural problem, they apply to the First-tier Tribunal in time, and they wait for a hearing date. Then, while that application is still sitting undecided, a second Form 4A arrives through the door - a fresh notice, a new proposed rent, a new effective date.

The renter's instinct is usually one of two things: panic that the first challenge has somehow been overtaken, or a worry that they now have to fight on two fronts at once. Both instincts lead to mistakes. The renter who withdraws the live application because "there's a new notice now" has thrown away a challenge that was already running. The renter who quietly starts paying the second notice's figure has, by conduct, agreed a rent they never had to.

The overlap of a pending tribunal application and a freshly served Form 4A is a genuine procedural trap, and it is showing up more often in the early weeks of the new regime - landlords getting impatient, landlords whose first notice was defective trying again, landlords who have changed agents and whose new agent serves a notice without checking what is already in train.

This walkthrough is for the renter who is in exactly that position: a Section 13 / Form 4 (or Form 4A) challenge already lodged and undecided at the First-tier Tribunal, and a new Form 4A now in their hands. It covers why this happens, the 52-week / 12-month gap rule and how the pending application bears on it, the decision tree for the second notice, what to do and what not to do, the holding letter to the landlord, and the letter to the tribunal.

Why a landlord serves a second notice mid-challenge

Understanding why the second notice has arrived helps the tenant work out what kind of problem they are looking at. There are four common reasons.

The landlord is impatient. The first notice is being challenged, the hearing is months away, and the landlord wants the increase moving. They serve a second notice in the hope of getting a fresh, unchallenged increase running in parallel. This is the most common reason and usually the weakest notice.

The first notice was defective and the landlord knows it. The landlord (or a new agent) has realised the first Form 4A had a procedural problem - wrong dates, wrong notice period, wrong tenancy details - and is serving a corrected version, hoping the tenant will engage with the new one and let the challenge to the old one fall away.

A change of agent. The landlord has switched letting agents mid-tenancy. The new agent, setting up their file, serves a Form 4A as a matter of routine without knowing - or without checking - that there is already a notice under challenge.

The landlord is testing whether the tenant will fold. Some second notices are simply pressure. The landlord is betting that two notices feel more intimidating than one, and that the tenant will agree a figure to make it stop.

None of these reasons makes the second notice automatically valid, and none of them makes the first challenge automatically dead. They just tell the tenant what they are dealing with.

The 52-week / 12-month gap rule

The single most useful piece of law here is the minimum gap between rent increases. Under the Section 13 regime as it applies after the Renters' Rights Act, a landlord cannot increase the rent more often than once in any 12-month period - and a Form 4A is not valid if the rent was last increased fewer than 12 months before the new notice's proposed effective date.

The question the renter has to answer is: what counts as the "last increase" when the first notice is still being challenged?

This is where the pending application matters. If the first Form 4A is still undecided at the tribunal, the rent has not yet been increased by it - the tribunal has not determined the rent, and the proposed increase in the first notice has not taken effect. So a second Form 4A whose proposed effective date falls inside 12 months of the previous actual increase (the one before the disputed notice) is vulnerable on the gap rule, because there has been no valid intervening increase to reset the clock.

The renter should not try to resolve this definitively on their own - the interaction of a pending application and a second notice is exactly the kind of point where a short advice-session with Shelter, Citizens Advice, or a housing solicitor is worth the time. But the renter should go into that advice session having worked out three dates: the date of the last rent increase that actually took effect, the proposed effective date in the first (challenged) notice, and the proposed effective date in the second notice. Those three dates frame the whole question.

The decision tree for the second notice

Once the renter has the dates, the second Form 4A falls into one of three categories. The renter works through them in order.

Category 1 - the second notice is premature on the gap rule. If the second notice's proposed effective date is fewer than 12 months after the last rent increase that actually took effect - and the first notice is still undecided, so it has not validly increased anything - the second notice is vulnerable. The renter does not have to "fight" it as a separate battle; they flag the defect, in writing, to the landlord and to the tribunal, and the second notice does not displace the first challenge.

Category 2 - the second notice has its own procedural defect. Independently of the gap rule, the second Form 4A might be defective on its face: wrong prescribed form, insufficient notice period (the minimum is two months), wrong tenant or property details, an effective date that is not a rent payment date. These are the same procedural defects that any Form 4A can carry. If the second notice is defective, it is challengeable on the same basis as the first - and the renter is now experienced at spotting exactly this.

Category 3 - the second notice is valid and properly timed. It is possible - less common, but possible - that the second notice is procedurally clean and properly timed: enough time has passed, the form is right, the notice period is right. In that case the renter has a genuine second notice to deal with, and the route is to challenge it at the tribunal in time, in the ordinary way, and ask the tribunal to deal with the two matters together (see below).

Most second notices served mid-challenge fall into Category 1 or Category 2. Category 3 is the exception, not the rule - but the renter should work through the tree honestly rather than assuming the second notice is bad.

What to do - and what not to do

A short, firm list, because the mistakes here are predictable.

Do not withdraw the live tribunal application. The first challenge is already running. A new notice does not overtake it, does not invalidate it, and does not make it pointless. Withdrawing it throws away a challenge the renter has already done the work to lodge. Keep it live.

Do not agree the second notice's rent by conduct. If the renter starts paying the figure in the second notice, the landlord can later argue the rent was agreed by conduct and the tribunal challenge is academic. Keep paying the existing rent - the rent that was lawfully payable before any of these notices - until the tribunal determines the matter. Paying the existing rent is not a breach; paying the new figure is an admission.

Do write to the landlord straight away. A short, dated holding letter that says the first notice is under challenge, the second notice has been received, and the renter does not accept it. This stops the landlord later saying the renter "went quiet" or "seemed to accept it".

Do write to the tribunal. The tribunal handling the live application should be told a second notice has arrived. They can then decide how to manage it - often by dealing with both notices in the same proceedings.

Do get an advice check. The overlap of a pending application and a second notice is a known grey area. A free advice session - Shelter, Citizens Advice, a county court duty desk, or a housing solicitor's initial consultation - is worth the hour. The renter does the date-gathering; the adviser confirms the route.

The holding letter to the landlord

[Tenant name]
[Property address]
[Phone] [Email]
[Today's date]

[Landlord or letting agent name]
[Address]

Dear [name],

Re: Form 4A rent increase notice dated [date of second
notice] - [property address]

I have received your Form 4A notice dated [date],
proposing a rent of GBP [amount] with effect from [date].

I am writing to let you know that I do not accept this
notice, for the following reasons:

1. I have an existing application to the First-tier
   Tribunal (Property Chamber), reference [tribunal ref],
   challenging your earlier notice dated [date of first
   notice]. That application has not yet been determined.
   The rent has therefore not been validly increased and
   the position is not settled.

2. [Where the gap rule applies:] The proposed effective
   date of your new notice falls fewer than 12 months
   after the last rent increase that actually took effect
   on [date]. As there has been no valid intervening
   increase, the new notice appears to be premature.

3. [Where there is a separate defect:] In addition, your
   new notice [describe the procedural defect].

I will continue to pay the rent that is lawfully payable -
GBP [existing rent] per [period] - pending the tribunal's
determination of my existing application. I am not
agreeing the rent proposed in either notice.

I am notifying the tribunal that this second notice has
been served.

Yours sincerely,
[Tenant full name]

The letter to the tribunal

[Tenant name and contact details]
[Date]

First-tier Tribunal (Property Chamber)
[Regional office]

Re: Application reference [tribunal ref] -
[property address]

I am the applicant in the above rent determination
application, which challenges a Form 4A notice dated
[date of first notice] and has not yet been determined.

I am writing to inform the tribunal that on [date] my
landlord served a further Form 4A notice, proposing a rent
of GBP [amount] with effect from [date]. A copy of the
second notice is enclosed.

I do not accept the second notice. [Briefly: it appears
premature on the 12-month gap rule, as there has been no
valid intervening increase / it carries the following
procedural defect: ...] I have written to the landlord to
say so, and a copy of that letter is enclosed.

I would be grateful if the tribunal could indicate how it
wishes the second notice to be dealt with - in particular
whether it can be considered within the existing
proceedings, so that the rent question is determined once
rather than across two separate applications.

Yours faithfully,
[Tenant full name]

Enclosures: copy of second Form 4A notice; copy of holding
letter to landlord.

The value of this letter is that it puts the tenant on the front foot. The tribunal now knows the full picture, the landlord cannot claim the tenant ignored the second notice, and the most likely outcome - both notices dealt with together, the rent determined once - is the one the tenant has asked for.

Sequencing: one determination, not two

The outcome a renter in this position should be aiming for is a single tribunal determination that resolves the rent, rather than two parallel applications grinding on separately.

If the second notice is premature or defective (Categories 1 and 2), the practical effect of flagging it is usually that it falls away and the original challenge proceeds to determine the rent. If the second notice is valid and properly timed (Category 3), the renter challenges it in time and asks the tribunal to consolidate - to deal with both notices in the same hearing so the rent is set once, on current evidence, rather than twice.

Either way, the renter's job is the same: keep the first application alive, keep paying the existing rent, document everything in writing, and let the tribunal manage the overlap. The renter does not have to choose between the two notices or fight a war on two fronts - they have to make sure the tribunal has the full picture and then let the process do its work.

Where the RentSOS check fits

The free check at rentsos.co.uk reads a Form 4A notice for procedural defects - the prescribed form, the notice period, the effective date, the 12-month gap, the tenancy details. When a second notice arrives mid-challenge, the check is exactly the tool for working out which category it falls into: run the second Form 4A through the check the same way the first one was run, and the procedural picture - premature, defective, or valid - becomes clear. The check handles the document analysis; the walkthrough above handles the overlap with the live application.