Rent increase calculator
Most section 13 notices that fail, fail on dates. Enter the last increase and when you plan to serve, and this works out the earliest the new rent can start, the latest date you can serve to hit it, and what the increase actually amounts to.
Dates
Whichever is more recent — that's what the 12 months runs from
The two months' notice runs from here
Rent
Must be no more than market rate — the tribunal can't go above what you propose
Earliest the new rent can start: 5 October 2026
Set by the two-month notice period. The 12-month rule allows 5 August 2026; two months' notice from your serve date allows 5 October 2026. The later of the two applies.
Earliest start date
5 October 2026
Bound by the two-month notice period
Latest date to serve
5 June 2026
To start on the 12-month anniversary
Increase
+£75/mo
£900 a year
Percentage change
+6.3%
Against the current rent
Before you serve
- Use Form 4A — the private rented sector section 13 notice. Form 4 is the social-housing version.
- Propose no more than market rate, and capture two or three dated comparables before you send it. The tribunal can't award more than you ask for, and there's no backdating — so an optimistic figure only costs you time.
- A rent review clause in the tenancy agreement no longer works. Section 13 is the only route.
The two rules, and why both matter
Under the Renters' Rights Act you can raise the rent once every 12 months, to market rate, and you must give at least two months' notice. Landlords tend to remember one rule and forget the other.
They bind independently. Serving three months early doesn't let the new rent start before the 12-month anniversary. Equally, waiting until after the anniversary doesn't waive the notice period — you still owe two months from the day you serve. The earliest valid start date is whichever of the two lands later, which is exactly what the calculator resolves.
One consequence worth planning around: if you want the increase to start on the anniversary, you have to serve two months before it. Miss that and the increase slips, because there is no way to compress the notice period.
For the tribunal route, what counts as market rate, and why proposing an optimistic figure now works against you, see the section 13 guide.
Rent increases — FAQ
How often can I increase the rent?
Once every 12 months, to market rate, under the Renters' Rights Act. The 12 months runs from the last increase, or from the start of the tenancy if there hasn't been one. Rent review clauses in the tenancy agreement no longer work — a section 13 notice is the only route.
How much notice do I have to give?
At least two months before the new rent takes effect. Both rules bind independently: serving early doesn't let you start sooner than the 12-month anniversary, and waiting past the anniversary doesn't remove the two-month notice period. The calculator applies whichever is later.
Which form do I use?
Form 4A — the section 13 notice for assured tenancies in the private rented sector. Form 4 is the social-housing version and stays in use there until 2027 at the earliest, so check you have the 'A'.
What if the tenant challenges the increase?
They can apply to the First-tier Tribunal, which determines the market rent. Two things are worth knowing before you pick a figure: the tribunal cannot order a rent higher than you proposed, and the determined rent applies from the date of determination with no backdating. So an over-optimistic ask has no upside — it just costs you months at the old rent.
Does this work for a tenancy that started before May 2026?
Yes. All assured tenancies in the private rented sector became periodic on 1 May 2026 and the section 13 route applies to them, whatever the original agreement said. If the tenancy has never had an increase, use the tenancy start date as the starting point.
Disclaimer: This calculator applies the 12-month and two-month rules to the dates you enter. It is general information for UK landlords, not legal advice, and it does not check whether your proposed rent is at market rate. A defective section 13 notice is ineffective — check the current form and dates before serving.
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