Form 4 vs Form 4A: the tenant walkthrough for the 1 May 2026 transition fortnight
In the seven days either side of 1 May 2026 the Section 13 regime switches from Form 4 to Form 4A. The date of service decides which rules apply - and the tribunal risk is very different between the two. Tenant walkthrough.
There is one rule for the whole transition fortnight, and it is short: the date a Section 13 notice was served decides which regime applies, not the date the increase is proposed to take effect.
That sentence matters because the tribunal risk is very different between Form 4 (old regime) and Form 4A (new regime). Get the form wrong, get the rules wrong, and you can get the response strategy wrong.
This is a tenant walkthrough of the seven days on either side of 1 May 2026 - Sunday 26 April 2026 to Friday 8 May 2026. Five scenarios, five tenant responses. England only. Plain English throughout.
The headline rule
Service date decides the regime.
- A Form 4 served before 1 May 2026 stays valid under the old rules even if the effective date falls after 1 May.
- A Form 4 served on or after 1 May 2026 is invalid - it must be Form 4A.
- A Form 4A served before 1 May 2026 is invalid - the form does not exist in law yet.
- A Form 4A served on or after 1 May 2026 is the correct form.
Every other decision flows from those four bullet points.
Why the tribunal risk is different
A Section 13 notice served before 1 May 2026 - even if the rent increase only takes effect after 1 May - is governed by the old rules. That means the tribunal can:
- Set the new rent higher than the landlord proposed.
- Backdate the new rent to the effective date on the notice.
- Leave you with a rent you cannot afford for the backdated period.
A Section 13 notice served on or after 1 May 2026 is governed by the new rules. The tribunal:
- Cannot set the new rent higher than the landlord proposed.
- Cannot backdate the new rent; it applies only from the tribunal's decision date.
That is a very significant difference. A notice served on 30 April 2026 for a 1 July 2026 effective date carries the old tribunal risk. A notice served on 1 May 2026 for the same 1 July effective date carries the new, much friendlier tribunal risk.
In the transition fortnight, the date on the notice matters more than it will at any other moment for years.
The five scenarios
Open the notice you received. Find two things: the date the landlord signed or dated the notice, and which form it is on (Form 4 is the current prescribed form; Form 4A is the new one). Then match yourself to one of the five scenarios below.
Scenario 1 - Form 4 served before 1 May, effective date also before 1 May
The landlord served a Form 4 in April 2026 proposing a rent increase effective on, say, 15 April 2026.
Is the notice valid? Subject to the usual checks (correct form, correct notice period, effective date at the start of a rental period, 52 weeks since any previous Section 13 increase), yes.
Tribunal risk? Old rules. The tribunal can set higher than the landlord proposed and can backdate.
What you do: normal Section 13 response. Check the three date fields, the notice period, the tenancy-type match. If you see defects, raise them. If not, you have three weeks from receipt of the notice to apply to the First-tier Tribunal on Form RR1. Consider negotiation before going to tribunal because of the "can set higher" risk. See how to build a comparables table.
Scenario 2 - Form 4 served before 1 May, effective date on or after 1 May
The landlord served a Form 4 in late April 2026 proposing a rent increase effective on, say, 1 June 2026.
Is the notice valid? Yes, provided the usual checks. The Form 4 service date (before 1 May) locks it into the old regime even though the effective date is after 1 May.
Tribunal risk? Old rules. The tribunal can set higher and backdate. The effective date after 1 May does not drag the notice into the new regime.
What you do: same as Scenario 1. This is the trickiest scenario from a tenant perspective because it looks like it should be post-1-May (the effective date is after the Act takes effect) but legally it is not. The "can set higher" tribunal risk applies. Negotiation is usually the safer first step unless the notice has clear procedural defects.
Scenario 3 - Form 4 served on or after 1 May
The landlord served a Form 4 on or after 1 May 2026 - possibly because they hadn't noticed the new form, possibly because they ran out of time to update paperwork.
Is the notice valid? No. Form 4 is not the prescribed form for a notice served on or after 1 May 2026. The notice is invalid on its face.
Tribunal risk? N/A - you don't need a tribunal to defeat the notice. You write back invalidating it.
What you do: reply in writing that the notice is invalid because it uses Form 4 rather than Form 4A, cite the date the Act took effect, and continue paying the existing rent. The landlord will need to serve a fresh notice on Form 4A. See the Template 2 wording later in this guide.
Scenario 4 - Form 4A served before 1 May
The landlord served a Form 4A - the new form - but dated the notice 30 April or earlier. Possibly they were keen to be ready.
Is the notice valid? No. Form 4A is not yet the prescribed form for a notice served before 1 May 2026. A notice served before 1 May must use the then-current Form 4. A Form 4A served before 1 May is invalid on its face.
Tribunal risk? N/A - you don't need a tribunal to defeat the notice.
What you do: reply in writing that the notice is invalid because Form 4A does not take effect until 1 May 2026 and the landlord's service date is before that. Continue paying the existing rent. The landlord can serve a fresh notice on Form 4A on or after 1 May.
Scenario 5 - Form 4A served on or after 1 May
The landlord served Form 4A on or after 1 May 2026 proposing a rent increase with a valid effective date.
Is the notice valid? Subject to the usual checks (correct form content, two-month minimum notice, effective date at the start of a rental period, 52 weeks since any previous Section 13 increase), yes.
Tribunal risk? New rules. The tribunal cannot set higher than the landlord proposed and cannot backdate. This is a tenant-friendly regime.
What you do: normal Section 13 response under the new rules. Check the two-month notice period, check the form content, check tenancy type. If you see defects, raise them. If the figure is too high, consider going to tribunal - the downside risk is gone. See what the rent tribunal actually measures.
The transition fortnight map
Here is the fortnight laid out by date, so you can find your spot quickly.
| Date | Scenario for notices served on this day | Valid form | Tribunal risk |
|---|---|---|---|
| 26 April 2026 (Sun) | Form 4 only | Form 4 | Old rules |
| 27 April (Mon) | Form 4 only | Form 4 | Old rules |
| 28 April (Tue) | Form 4 only | Form 4 | Old rules |
| 29 April (Wed) | Form 4 only | Form 4 | Old rules |
| 30 April (Thu) | Form 4 only (last day of old regime) | Form 4 | Old rules |
| 1 May 2026 (Fri) | Form 4A only (regime switches) | Form 4A | New rules |
| 2 May (Sat) | Form 4A only | Form 4A | New rules |
| 3 May (Sun) | Form 4A only | Form 4A | New rules |
| 4 May (Mon) | Form 4A only | Form 4A | New rules |
| 5 May (Tue) | Form 4A only | Form 4A | New rules |
| 6 May (Wed) | Form 4A only | Form 4A | New rules |
| 7 May (Thu) | Form 4A only | Form 4A | New rules |
| 8 May (Fri) | Form 4A only | Form 4A | New rules |
The rule is blunt. There is no grace period for landlords using the old form after 1 May and no early window for the new form before 1 May.
Four date checks for every notice in the fortnight
Whatever scenario you are in, four date checks take two minutes and resolve almost every ambiguity.
- What date did the landlord sign the notice? Often at the bottom near the signature block. Sometimes on a covering letter.
- What date was the notice served on you? Date received by post, by hand, or in your letterbox. Save envelopes.
- Which form is it? Form 4 will say "Form 4" or reference the Housing Act 1988 prescribed form. Form 4A will say "Form 4A" or reference the Renters' Rights Act 2025.
- What is the proposed effective date? Usually stated clearly on the face of the notice.
If the service date is before 1 May and the form is Form 4 - Scenario 1 or 2, old regime. If the service date is on or after 1 May and the form is Form 4A - Scenario 5, new regime. Any other combination is a defect.
The three-week rule on referrals
One tenant-protective rule carries across both regimes: if you want to refer the rent increase to the First-tier Tribunal, you must do so before the new rent would take effect.
Under Form 4 (old regime), that is often one month from the notice date. Under Form 4A (new regime), you have two months from the notice date, because the minimum notice period is two months.
In the transition fortnight this matters particularly. A Form 4 served on 29 April 2026 for a 1 June 2026 effective date is still on the old timescale - you have until 31 May to refer.
What the landlord might try, and what to do
A few things you will see in the transition fortnight.
"The rules haven't quite started yet, we're using the old form"
If the service date is on or after 1 May, Form 4 is invalid regardless of what the landlord intends. Reply invalidating it.
"The new rules mean I can put the rent up whenever I like"
No. Section 13 (via Form 4A) is the only route, with two months' notice, and tribunal protection.
"The tribunal will set it higher so you shouldn't challenge"
Only true under the old regime. Under Form 4A the tribunal cannot set higher than the landlord proposed.
"I'll redate the notice to 1 May even though I served it last week"
Redating a served notice after the fact is not lawful. The service date is when the notice reached you. If the envelope is postmarked before 1 May, that is the service date.
Three response templates
Template 1 - Scenario 1 or 2 (Form 4 served before 1 May)
Dear [landlord],
Thank you for your Section 13 notice dated [notice date].
I am considering my response. Before replying substantively I am checking the notice against the required fields and will be in touch further within [one month / two weeks].
I will of course continue to pay the existing rent of [£amount] in the meantime.
Kind regards, [Your name]
Template 2 - Scenario 3 (Form 4 served on or after 1 May)
Dear [landlord],
Thank you for your Section 13 notice dated [notice date].
I understand that from 1 May 2026 the prescribed form for a Section 13 rent increase is Form 4A under the Renters' Rights Act 2025. Your notice is on the previous Form 4.
For that reason the notice is not a valid Section 13 notice and does not take effect. I will therefore continue to pay the existing rent of [£amount].
Should you wish to propose a rent increase, please serve a fresh notice on Form 4A with at least two months' notice. I am happy to respond to that when it arrives.
Kind regards, [Your name]
Template 3 - Scenario 5 (Form 4A served on or after 1 May)
Dear [landlord],
Thank you for your Section 13 (Form 4A) notice dated [notice date].
I am reviewing the notice and the proposed rent of [£amount]. I will reply substantively by [date - two to three weeks from receipt].
I will continue to pay the existing rent of [£amount] in the meantime.
Kind regards, [Your name]
First-48-hours protocol for a transition-fortnight notice
The two days after you receive the notice.
- Photograph or scan the notice and the envelope.
- Note the date received and the date the landlord signed.
- Note which form (Form 4 or Form 4A).
- Check your rent day and confirm the effective date on the notice lands at the start of a rental period.
- Do not pay the new rent yet.
- Do not reply in the first 24 hours unless you are confident which scenario applies.
- Run the free check at RentSOS for a second pair of eyes.
Clear head, right form, right rules.
What about ambiguous or undated notices?
If the notice is undated, or the envelope has a postmark that differs from the signed date, keep both pieces of evidence. The service date under Section 13 is generally when the notice reached you - so an envelope with a 30 April postmark and a 2 May signed date is arguably still a pre-1-May notice, but the ambiguity is the landlord's problem, not yours.
If the notice cannot be read clearly as Form 4 or Form 4A, treat that as a further defect. A prescribed form is not optional - the format exists for a reason.
Frequently Asked Questions
+The effective date on my notice is after 1 May 2026. Does the new regime apply?
Not automatically. The regime is decided by the **service** date, not the effective date. A Form 4 served before 1 May 2026 stays under the old rules even if the effective date is in June or July 2026. A Form 4A served on or after 1 May 2026 is under the new rules regardless of effective date.
+Can my landlord post-date a notice to 1 May 2026 to get the new rules benefit?
Post-dating a notice doesn't change its service date. The service date under Section 13 is generally when you received the notice. If you received it on 28 April, it is an April-served notice regardless of the date the landlord wrote on it. Keep envelopes as evidence.
+What if my notice is on the wrong form - can the landlord just correct it?
No. A defect on the face of the notice cannot be "cured" after service. The landlord would need to serve a fresh notice. So a Form 4 served on 2 May is invalid; the landlord can serve a fresh Form 4A on, say, 5 May, and the two-month notice period then starts again from the new service date.
+Does the "can set higher" tribunal risk apply to a Form 4 served on 30 April for a 1 September effective date?
Yes. Under the old regime the tribunal could set higher than the landlord proposed and could backdate. A Form 4 served before 1 May carries that risk, even if the effective date is months after 1 May. For that reason, negotiation is usually the safer first step with a late-April Form 4 unless there is a clear procedural defect.
+I received a notice on 30 April and another on 5 May - which wins?
The later notice would normally supersede the earlier only if the earlier is formally withdrawn. If both are on the table, challenge the 30 April Form 4 first (if it is defective) and respond to the 5 May Form 4A on its merits. Two notices about the same tenancy in a week is itself a procedural mess worth raising.
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