The rent review conversation to have this September, not later
September sits at the precise point in the year where a landlord who plans their rent reviews carefully can act now and have a November start date in place before the end of the year. One who does not plan this month risks deferring an increase into January, losing several weeks of additional income in the process. The mechanics of the Section 13 process, introduced on 1 May 2026 as the only lawful mechanism for rent increases on assured periodic tenancies in England, make September a particularly useful moment to review where each property in a portfolio stands.

The arithmetic that makes September count
Form 4A, the prescribed government form for Section 13 rent increases, requires at least two months' written notice before the proposed new rent takes effect. Two months' notice served in September produces a new rent date no earlier than November. Two months' notice served in October produces one no earlier than December. Leaving the conversation until October narrows the window for a 2026 increase considerably. Leaving it until November means the earliest the higher rent can begin is January 2027.

The 12-month rule compounds this. Only one increase is permitted per 12-month period, and the clock runs from when the last increase took effect, not from the date notice was served, and not from the tenancy start date if a previous increase has been made. A landlord who secured an increase that landed in November 2025 can seek the next one from November 2026. Serving a Form 4A in September 2026 for a November 2026 start captures that window cleanly. Missing September and moving to October means either a December start or, if the timing does not fall cleanly on a rent payment date, a slip into January.

What Form 4A requires
Form 4A is available free from gov.uk and must be used exactly as published. A letter, an email, or a landlord-drafted document containing the same information does not satisfy the Section 13 requirement. The form must include the address of the property, the names of the landlord and tenant, the current rent, the proposed new rent, and the proposed effective date. For a monthly tenancy, that date must fall on the first day of a new rent period, meaning the same date each month that rent is normally due. The completed form must be served on every named tenant individually, and a copy should be retained along with evidence of service.

Once served, the tenant has until the proposed rent start date to refer the increase to the First-tier Tribunal if they consider it above the open market rate. A referral suspends the increase until the tribunal determines the market rent. The tribunal cannot set the rent higher than the landlord proposed. A well-evidenced, market-grounded proposal is both less likely to be challenged and better positioned if a challenge is made.

What market evidence looks like in September 2026
The Section 13 process does not specify a required format for rental comparables, but evidence that demonstrates the proposed rent reflects current market conditions is what protects a landlord in the event of a tribunal referral. Current asking rents for comparable properties in the same area, agreed rents from recent lettings if accessible through a managing agent, and the rental data available from Zoopla and Rightmove's rental trackers all provide a basis for demonstrating that a proposed increase reflects the market.

Zoopla's June 2026 Rental Market Report shows average UK rents at £1,321 per month, up 2.1% year-on-year, with strong variation by market. A proposed increase grounded in what comparable properties in the immediate area are currently achieving is the increase best placed to be accepted without challenge and, if challenged, upheld.

September is the month to open this review. November is when the conversation pays off.

Talk to our lettings team about managing your rent reviews