Since 1 May 2026 there is exactly one lawful way to increase the rent on an assured tenancy: a Section 13 notice on the prescribed form — Form 4A. Rent review clauses in tenancy agreements are unenforceable, informal agreements have no effect, and a notice with the wrong dates on it is simply invalid. This guide walks the process end to end.
Rules verified against gov.uk guidance at the review date. Use the free Rent Increase Calculator to apply them to your actual dates.
The four rules every valid notice satisfies
- The prescribed form. The notice must be on Form 4A. A letter, email, or message proposing a new rent is not a Section 13 notice.
- At least two months' notice. The new rent cannot start sooner than two months after the notice is served.
- Once every 12 months. Rent cannot rise more than once in any 12-month period — the earliest new increase is 52 weeks after the last one (or after the tenancy started).
- Rent-period alignment. The new rent must start on the first day of a rent period. If rent is due on the 1st, a start date of the 15th invalidates the notice.
Step by step
Step 1 — Establish your market evidence
The proposed rent should be defensible as market rent. Before you pick a number, gather comparables: similar properties, same area, currently advertised or recently let. Keep them — if the increase is challenged, this is your case.
Step 2 — Work out the earliest valid start date
Take the later of: (a) two months from service, and (b) 52 weeks from the last increase. Then roll forward to the next rent-period start day. If you're posting the notice, add at least two working days for deemed service. The calculator does all of this for you.
Step 3 — Complete and serve Form 4A
Complete the form with the current rent, proposed rent, and the start date from Step 2. Serve it the way your tenancy agreement permits, and keep proof of service — a certificate of posting, a delivery photo, or a written acknowledgement.
Step 4 — The tenant's options
The tenant can accept (pay the new rent from the start date) or refer the notice to the First-tier Tribunal before the start date. If they refer it:
- The tribunal decides what the market rent is — it can confirm or reduce your proposed rent, but cannot set it higher.
- The determined rent is not backdated: it applies from the tribunal's decision date (or the notice's start date if the decision comes earlier).
- The tribunal can defer the increase by up to two months where paying from the decision date would cause hardship.
A tribunal referral costs the tenant nothing and delays the increase without risk of a higher rent. Your protection is a sensible number: an increase pitched at demonstrable market rent rarely gets referred, and holds up when it does. An aggressive number invites a referral that can cost you months of the increase.
The mistakes that invalidate notices
- Using a letter or an old form instead of Form 4A
- A start date that isn't the first day of a rent period
- Less than two months between service and the start date
- Serving within 52 weeks of the previous increase
- No proof of service when the tenant disputes receiving it
Any of these means starting again — with a fresh two-month clock.
Keep the record
Whatever happens, file: the served Form 4A, your proof of service, your comparables, and any tribunal correspondence. Under the new regime your next increase, and any future possession claim, both lean on this history being findable.
Sources
Change log: 20 Aug 2026 — first published.
