Section 13 notice: the mistakes that invalidate a rent increase
A section 13 notice fails on mechanics more often than on the amount. The wrong form, short notice, a misaligned start date or a second increase inside 12 months all leave the old rent payable.
Published ·4 min read
A section 13 notice is the only way a landlord in England can raise the rent on an assured periodic tenancy, and since 1 May 2026 the mechanics are strict: prescribed Form 4A, two months' notice, one increase in any 12 months, a start date on a rent period boundary. Miss any of these and the notice is invalid — the old rent stays payable and the clock restarts. These are the defects that actually catch landlords.
1. Not using Form 4A
Section 13(2) of the Housing Act 1988 requires the prescribed form, which since 1 May 2026 is Form 4A. The old Form 4 no longer works, and neither does a letter or email — even one containing every piece of information the form asks for. The prescribed form carries guidance notes for the tenant, including how to challenge; a home-made version omits them and fails for that reason alone. Download the current form from GOV.UK each time.
2. Less than two months' notice
The new rent cannot start earlier than two months after the notice is served (s.13(2), as amended by section 6 of the Renters' Rights Act 2025). Count from service, not from the date you signed the form — and if your tenancy agreement deems postal service to occur two working days after posting, count from then. A date even one day short invalidates the notice.
3. A start date that misses the rent period
The new rent must take effect on the first day of a new period of the tenancy. Monthly tenancy running from the 10th? The start date must be the 10th of a month. The common failure is counting exactly two months from service and writing down whatever date that produces — which usually lands mid-period. Fix the period boundary first, then check it clears two months.
4. A second increase inside 12 months
Rent can rise once in any 12 months, and the period runs from the date the last increase took effect — not from when the previous notice was served. A landlord who served in March for a June start cannot serve again the following March expecting a May start; nothing can take effect before the June anniversary. Where the last increase was set by the tribunal, count from the date the tribunal's rent took effect.
5. Treating the rent as due while a tribunal challenge is pending
The tenant can refer the notice to the First-tier Tribunal (Property Chamber) at any time before the start date, free of charge. Once they have, the increase does not take effect on the date in the notice: the tribunal determines the open market rent, the new rent is the lower of that and your proposed figure, and it applies from the date the tribunal directs — the Renters' Rights Act 2025 removed backdating. Demanding the increased rent, or serving arrears paperwork based on it, while the referral is pending is treating a proposed rent as a real one. It is not, yet.
6. Relying on a rent review clause instead
Any contractual mechanism for raising the rent — fixed uplift, index-linking, "market review" — has been of no effect since 1 May 2026 (s.13(4A) of the 1988 Act). So has an informal agreement: even an increase the tenant is happy with must go through Form 4A. Invoicing an increase under an old clause simply means the increase never happened, and overpayments are recoverable. More in rent review clauses are void.
What an invalid notice costs
There is no penalty for a defective section 13 notice — the cost is time. The old rent remains payable, and a fresh, correct notice restarts the two-month clock. On a typical monthly tenancy, a defect discovered late can push the increase back a full quarter. The tenant, meanwhile, risks nothing by checking: the tribunal cannot set a rent above the landlord's own figure.
Get the mechanics checked
Our guided notice validates each of these points before you serve: current Form 4A, the two-month count from your service method, the period boundary, and the 12-month rule against your last increase.
Related: Form 4A: how the section 13 notice works · rent review clauses are void — what to do · section 8 grounds and notice periods · what replaced the AST.