A Section 13 notice looks simple. One form, two months' notice, one new rent figure. But every month, landlords have rent increases overturned at the First-tier Tribunal because they got a tiny detail wrong. Here are the seven mistakes that void a Section 13 notice in 2026, and how to avoid each one.
Why getting it right matters
A Section 13 notice is the only lawful way to increase rent on a periodic tenancy in England after the Renters' Rights Act 2025 came into force. If your notice is invalid, the proposed rent does not take effect. You cannot serve a fresh notice for another 12 months in most cases, so a void notice can lock you out of an increase for a full year.
Worse, a tenant who pays the higher amount on a void notice can later reclaim it as an overpayment. The cost of getting this wrong is rarely a small amount.
Mistake 1: Using the wrong form
The prescribed form for a Section 13 rent increase is Form 4, published by the Ministry of Housing, Communities and Local Government. It is the only valid format. Word documents that look similar, older versions of the form, and "rent increase letters" you might find online are not acceptable.
The form was updated in 2026 to reflect the changes brought in by the Renters' Rights Act. If you serve a pre-2026 version, the notice is void on its face. Always download the current Form 4 from gov.uk on the day you serve it, or use a generator that pulls the latest version.
Mistake 2: Getting the effective date wrong
The effective date is the date the new rent starts. This is the single most common reason Section 13 notices are voided. There are three rules that all have to be satisfied at once:
- At least two months from the date of service. Service date counts as day zero. If you serve on 1 March, the earliest effective date is 1 May.
- The first day of a rent period. If the tenant pays on the 5th of each month, the effective date must be the 5th of a month, not the 1st.
- At least 12 months after the last rent increase. If you increased the rent on 1 June 2025, the earliest new effective date is 1 June 2026, regardless of when you serve the notice.
Get any one of these wrong and the notice is void. The two-month rule trips up landlords who serve by first class post and forget that postal service adds two business days before the clock even starts.
Mistake 3: Serving by an unacceptable method
Acceptable service methods are personal delivery, first class post to the rental property, and email only if the tenancy agreement names email as a valid service method. If your tenancy agreement is silent on email, serving by email alone is not valid service.
Recorded delivery and signed-for post are fine because they include first class post. WhatsApp, text, voicemail, and verbal notice are not.
The trap most landlords fall into: they send a polite email to the tenant explaining the increase, then post the form a week later. The tribunal often treats the email as the service date because that was the first communication of the proposal. If the email predates the form, the notice may be void.
Mistake 4: Proposing a rent above market rate
You can propose any rent you like on the form. But if the tenant challenges at the First-tier Tribunal, the Tribunal will set the rent at what it considers market rate for the property. The Tribunal cannot award more than you proposed, but it can reduce your proposal.
If you propose £1,400 and market rate is £1,200, the new rent becomes £1,200. If you propose £1,800 hoping to bargain, you are giving the tenant a clear incentive to challenge, and you may end up with less than you would have got by proposing £1,400 honestly.
Use local letting comparables for the same property type, bedroom count, and area. Rightmove, Zoopla, and the local letting agents' boards give you a defensible figure. Save a screenshot dated to the day you posted the notice.
Mistake 5: Missing the once-per-year window
Under the Renters' Rights Act, landlords can only increase rent once every 12 months. This is calculated from the effective date of the previous increase, not the date you served the previous notice.
If you increased rent with an effective date of 1 January 2026, your next effective date must be 1 January 2027 or later. Serving a fresh Section 13 on 1 November 2026 with an effective date of 1 January 2027 is fine. Serving on 1 November 2026 with an effective date of 1 December 2026 is void.
The clock also resets if you increase rent by mutual written agreement outside the Section 13 process. A rent renegotiation logged in writing counts as an increase for the purposes of the 12-month rule.
Mistake 6: Forgetting the tenant's right to challenge
The form must include information about the tenant's right to challenge the new rent at the First-tier Tribunal (Property Chamber). The current Form 4 includes this language. If you handwrite or retype the form and accidentally omit any of the required notes about challenge rights, the notice is void.
The tenant must apply to the Tribunal before the new rent is due to take effect. If they miss that deadline, they cannot challenge. If they apply on time, the rent does not change until the Tribunal decides. So a sensible tenant who wants to challenge will apply quickly.
Mistake 7: No proof of service
If you cannot prove when and how the notice was served, you cannot prove the notice is valid. The Tribunal will assume against you. This is the silent killer for landlords who think a verbal "I told them face to face" is enough.
What counts as proof:
- A certificate of posting from the Post Office, dated
- A signed acknowledgement from the tenant of personal delivery
- An email delivery receipt, with the tenancy agreement clause that permits email service stored alongside
- A timestamped photograph of the notice being posted through the letterbox, where personal delivery is used
Whatever method you use, save the proof in an append-only audit trail before you do anything else. PropReady timestamps and stores every notice you generate, with the proof of service attached, so there is no question later about when service happened.
What to do next
If you are about to serve a Section 13 notice, work through this list before you send it:
- Latest Form 4, downloaded today
- Effective date that satisfies all three rules
- Service method that is permitted by your tenancy agreement
- Proposed rent backed by current local comparables
- At least 12 months since the previous increase
- Required tenant challenge information present on the form
- Proof of service captured the same day
If you tick every box, your notice will stand. If you skip even one, you may be giving up a year of increased rent.
City-specific deposit and licensing context
A Section 13 notice will not save you if the underlying tenancy is non-compliant on other fronts. For city-specific rules that interact with rent increases, see:
- London deposit protection rules
- Manchester selective licensing
- Birmingham HMO licensing
- Leeds HMO licensing
- Bristol selective licensing
Related reading on the wider tenancy regime: Section 21 abolition, choosing the right Section 8 ground, and PRS Database registration.
This article is general guidance, not legal advice. For your specific tenancy, consult a qualified housing solicitor or use PropReady's AI document generator to produce a compliant Section 13 notice with the current form and pre-checked dates.