Section 13 — Rent increases

Before 1st May 2026 there were three common ways to increase rent on an Assured Shorthold Tenancy. A rent-review clause buried in the tenancy agreement. A renewal at the end of the fixed term, on whatever new figure the parties agreed. Or a Section 13 notice if the tenancy had rolled into a periodic. From 1st May 2026, only the last route survives — and the form for it has changed.

Section 13 of the Housing Act 1988, as amended by the Renters' Rights Act 2025, is now the only lawful way to increase the rent on an Assured Periodic Tenancy. The notice is served on the prescribed form, which is Form 4A. Get the form, the timing or the figure wrong and the increase does not take effect.

What changed in one paragraph

Rent-review clauses in pre-1st-May tenancy agreements are void for the purpose of increasing rent. They no longer have legal effect, even if both parties signed up to them. The fixed-term renewal route is gone because fixed terms are gone — every assured tenancy is now periodic from the moment it starts. Any rent increase, on any tenancy, must run through Form 4A.

The Form 4A rules

• Two months minimum notice. The new rent cannot take effect earlier than two months from the date the notice is properly served on the tenant.
• Once per year. A landlord can only serve a Form 4A once in any twelve-month period on the same tenancy. A second notice inside the year is invalid even if the tenant would consent.
• Reflects market rent. The figure proposed must be no more than the open-market rent for a similar property in the area. Tribunals routinely test this against comparable lets.
• Effective from the start of a rental period. The new rent kicks in from the next rent-period boundary after the two-month notice expires, not in the middle of a month.

The tribunal can only go down

This is the structural change landlords often overlook. If the tenant disagrees with the proposed increase they can apply to the First-tier Tribunal (Property Chamber) to have the rent determined. Under the Renters' Rights Act, the tribunal's powers are now strictly bounded:

• The tribunal can confirmthe landlord's proposed rent.
• The tribunal can reducethe rent below the landlord's proposed figure if the evidence shows the proposed rent is above market.
• The tribunal cannot raisethe rent above the landlord's proposed figure under any circumstances. It is confirm-or-reduce only.

Undue hardship and deferred start dates

If the tribunal determines a rent increase that would cause the tenant undue hardship, it can defer the start date by up to two months from the date the new rent would otherwise have taken effect. This is a discretionary power, not a tenant right of veto, but it is a real tool the tribunal uses when an increase would otherwise force a vulnerable tenant out.

The tenant's separate challenge — the first six months

Section 13 sits alongside an entirely separate tenant right introduced by the Renters' Rights Act: the right to challenge the initial rent of any tenancy at the First-tier Tribunal in the first six months. This is not an increase challenge — it is a challenge to the starting rent itself, and it applies even where there has been no Form 4A notice. The tribunal's confirm-or-reduce-only constraint applies here too, but landlords entering tenancies at speculative rents need to know that the tenant can test that figure for the first six months.

Section 13 notices served before 1st May 2026

A Section 13 notice that was lawfully served before 1st May 2026, even if the increase only takes effect after 1st May, follows the old rules. Tribunals retain the power to backdate increases on these legacy notices. Anything served on or after 1st May follows the new Form 4A regime.

Service rules

• First-class post — deemed served on the second working day after posting. Add the buffer to your two-month calculation.
• Hand delivery — same day if before 4:30pm; next working day if after 4:30pm or via the letterbox.
• Email — only valid if the tenancy agreement contains an explicit clause authorising service of statutory notices by email. Most pre-1st-May ASTs do not.

Tribunal — practical points

• The tenant applies on form MR1 (Application to a First-tier Tribunal — Property Chamber). A tribunal application fee applies; the most up-to-date amount is on the gov.uk fees schedule.
• The tribunal will fix a determination based on comparable open market rents. Both sides can submit evidence; landlords often underestimate how much weight the tribunal places on Rightmove and Zoopla snapshots from the same postcode.
• The tribunal's decision is binding for the rent period it covers. The landlord can serve a fresh Form 4A twelve months later.

Practical workflow

• Set a calendar reminder twelve months from each tenancy start date. That is your Form 4A window.
• Decide the new rent figure first, evidence-led, against comparable lets. The figure on the form is the figure you want.
• Build in a working-day service buffer when calculating the earliest effective date. Two months from posting is not the same as two months from deemed service.
• Serve the Form 4A by first-class post with proof of postage, or hand-delivered with a witness photograph. Keep both in your evidence file in case the tribunal route follows.

This page is general guidance, drafted to reflect the requirements of the Renters' Rights Act 2025. It is not legal advice on a specific tenancy. If your case is contested at tribunal, get named legal advice — comparable-rents arguments often turn on a single piece of evidence.