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 — the 52 weeks runs from here
The two months' notice runs from here
Any date rent falls due. The new rent must start at the beginning of a rental period — give us one and we'll align the answer
Rent
Must be no more than market rate — the tribunal can't go above what you propose
Earliest the new rent can start: 15 November 2026
Set by the two-month notice period. The 52-week rule allows 15 September 2026; two months' notice from your serve date allows 15 November 2026. The later of the two applies.
One more rule this date doesn't yet account for
The new rent must take effect at the beginning of a period of the tenancy, not part way through one. If rent falls due on the 5th, a notice specifying the 20th is invalid however much notice you gave. Add a rent due date above and we'll move the answer to the next period start for you.
Earliest start date
15 November 2026
Bound by the two-month notice period
Latest date to serve
15 September 2026
To start on the earliest date above
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 a year, to market rate, and you must give at least two months' notice. Landlords tend to remember one rule and forget the other. The annual test is expressed as 52 weeks since the last increase took effect, not twelve calendar months — usually a day or two apart, and this calculator works in weeks.
They bind independently. Serving three months early doesn't let the new rent start before the 52-week date. Equally, waiting until after it 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.
There is a third rule, and it is the one that most often invalidates an otherwise careful notice: the new rent must take effect at the beginning of a period of the tenancy. If rent falls due on the 5th and your notice specifies the 20th, the notice is defective no matter how much notice you gave. Enter a rent due date and the calculator moves the answer to the next period start.
One consequence worth planning around: if you want the increase to start on the earliest date available, 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 a year, to market rate, under the Renters' Rights Act. The statutory test is 52 weeks rather than twelve calendar months, running from the date the last increase took effect — or from the start of the tenancy if there hasn't been one. The difference is a day or two, and this calculator works in weeks so it doesn't cost you them. 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 52-week date, and waiting past it doesn't remove the two-month notice period. The calculator applies whichever is later, then aligns the result to the start of a rental period.
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 52-week, two-month and rental-period 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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