Rent increases: the figure you propose is now the ceiling

A quick note first. This is general information to help you brief whoever builds your website, and to prompt a conversation with your own adviser. It is not legal advice, and it describes the position for private assured tenancies in England. Everything below is taken from the legislation as currently in force and from published tribunal decisions, all linked.

In a flat on Lower Chatham Street in central Manchester the rent was £1,650 a month. The landlord served notice proposing £1,700 from 18 August 2026. The tenant challenged it. On 17 September 2026 the First-tier Tribunal determined the market rent at £1,450 a month, with effect from 18 September 2026.

The landlord asked for £50 more and ended up £200 a month worse off than before they started.

That is not a tribunal in a bad mood. It is the arithmetic the Renters' Rights Act 2025 put in place, and a good deal of the commentary about it is still describing the old rules.

What actually changed

There are now two separate ways a tenant can put a rent in front of the tribunal, and they work differently. Mixing them up is where most of the confusion comes from.

Challenging a rent increase. The tenant applies under section 14(A3) of the Housing Act 1988. The tribunal determines the open-market rent under section 14(1), and section 14ZB then decides what the tenant actually pays. Subsection (5) says: "The new rent amount is... (a) the open-market rent, if lower than the proposed rent, and (b) otherwise, the proposed rent."

Read that twice, because it is the whole story. The number you wrote in the notice is the maximum. It is not the starting point for a negotiation and it is not a figure the tribunal can improve on. There is also no floor. Nothing in that wording stops the tribunal landing below the rent the tenant is already paying, which is exactly what happened in Manchester.

Challenging the rent itself in the first six months. This one is newer to most people. Under section 14(A1) a tenant on an assured tenancy, other than a relevant low-cost tenancy, can apply to challenge the rent they are paying, with no increase notice involved at all. Section 14(A2) bars it once more than six months have passed since the tenancy began, and bars it where the rent is already payable pursuant to a previous determination under section 14. There is a further bar in the commencement regulations where the tenant had already applied under the old section 22 and did not withdraw it.

Section 14ZA then sets the cap, and it is different again: "the open-market rent, if lower than the tenancy rent, and otherwise, the tenancy rent", the tenancy rent being what was payable immediately before the determination.

The part worth noticing is the effective date. The tribunal directs it, and section 14ZA(5) says only that it "must not be earlier than the date of the application". So a reduction can run from the day the tenant applied rather than from the day of the decision, which leaves rent already collected for that period to be sorted out between the parties.

So in the first six months of a tenancy, if the tenant applies, the tribunal can confirm the rent or lower it and nothing else. And the rent on the agreement usually started life as a figure on your website.

The increase can still go up, and that matters

It would be easy to read the Manchester decision and conclude the tribunal now always cuts. It does not. In a flat at 239 Ramsgate Road in Margate the rent was £1,030 and the landlord proposed £1,250 from 1 August 2026. On 7 September 2026 the tribunal determined £1,100, effective 1 October 2026. An increase, just a smaller one than asked for.

The pattern across the decisions is not hostility to landlords. It is that the tribunal determines an open-market rent on the evidence in front of it and then applies the cap. Where the proposed figure is defensible, it largely survives. Where it was reached by rounding up and hoping, it does not, and the downside now runs in one direction only.

One change that catches people out

The notice period moved. Section 13 now requires two months' notice of the new rent taking effect, after section 6 of the Renters' Rights Act 2025 substituted two months for the old minimum period and omitted the table that set it. That old minimum depended on the length of the tenancy period, and for a monthly tenancy it was one month, which plenty of agents have been diarising for years. A tribunal decision on a flat in Bolton makes the point in passing: because that notice was served before 1 May 2026, "the previous rules applied and only one month's notice is required". For anything served now, it is two.

Where the figure usually comes from

Here is the part that belongs to us rather than to the lettings press.

Ask an agent where the number in a section 13 notice came from and the honest answer is often a rental valuation: sometimes a proper one with an inspection, often a desktop figure, and increasingly a number that an instant valuation tool on the agency's own website produced from a postcode, a bedroom count and a property type.

A tribunal determines the open-market rent for that dwelling, with its actual size, layout, condition and terms, against comparable lettings. A number generated from four form fields knows none of that. It does not know the flat is 39 square metres, that the second bedroom is a box room, that the boiler has been failing since March, or that the three comparables within a hundred metres are all furnished and this one is not.

None of which makes an instant valuation tool a bad thing. It is one of the most effective lead generators a letting agency website has, and we build them. It makes it a lead generator that should be honest about what it is.

Six things worth changing on the website

1. Call the output an estimate, and show a range. A range invites the conversation. A precise number invites someone to treat it as a valuation, and the first person to do that is often the landlord.

2. Say what it is based on, in one line, under the number. Asking price data for similar properties in the postcode, not an inspection. That sentence costs nothing, and it is what keeps a marketing tool from reading as a professional opinion.

3. Put the inspection prompt in the result, not in the small print. The thing that makes a figure defensible is somebody having been inside the property. Your tool should say so while the landlord is still reading it.

4. Write the rent review page, because almost nobody has one. What a section 13 notice is, the two months' notice, the fact that there are rules on how soon after the last increase a new rent can start, that the tenant can challenge it, and that on a private assured tenancy under the current rules the tribunal cannot award more than was asked. Do not write the timing rule from memory: it is counted in weeks rather than months, with exceptions, and it is set out in section 13 itself. Have the page checked by whoever advises you on compliance before it goes live, because it is a page tenants will quote back at you.

5. Make the evidence trail part of the process. Dated photographs, the inspection record, the comparables actually used and whether they were advertised or agreed rents. Much of that already exists in the CRM. Whether any of it survives into the file you would hand a tribunal is a different question.

6. Check what your valuation tool promises. A tool that reads as a guarantee of achievable rent is worth fixing long before anybody tests it.

Do not read the older decisions as a guide

One trap, and it is an easy one. The old rules have not been switched off, and under those old rules the tribunal could determine a rent above the one the landlord proposed. Everything above about a ceiling applies to the new regime only.

The old rules still apply to social housing assured tenancies. The commencement regulations brought the new rules in for assured tenancies that are not social housing assured tenancies only. A relevant low-cost tenancy, the phrase the Act uses, means an assured tenancy of social housing where the landlord is a private registered provider, so for most private agents this is about any social housing stock they touch rather than about their cheaper lettings. The Act gives those tenancies a permanent track of their own, in a new section 13A.

The old rules also still apply where a section 13 notice was given before 1 May 2026 proposing a new rent to take effect on or after that date, and the tenant had either not yet referred it or referred it without a determination being made. Regulation 8 keeps sections 13(4) and 14 in the form they had immediately before 1 May 2026 for those tenancies, until the tribunal determines a rent, until both parties give written notice that they no longer require one, or until referral becomes time-barred, which happens if the notice was not referred by the date the new rent was due to take effect.

It matters because under the old rules the tribunal could backdate the new rent to the date in the landlord's notice, and it still does in those cases. A decision on a flat in Penge shows what that looked like. The notice was dated 21 November 2025 and proposed a new rent from 1 February 2026; the tribunal decided it on 21 May 2026 and set the rent from 1 February 2026, nearly four months earlier. That notice pre-dates the new regime altogether rather than being saved by regulation 8, which only reaches notices proposing a rent to take effect on or after 1 May 2026. The Bolton decision is the saved case proper: a notice served on 29 April 2026 proposing 18 June 2026, decided on 11 August 2026 and backdated to 18 June 2026.

Neither tells you anything about what happens to a notice you serve now.

Under the new rules the rent takes effect from the beginning of the new period specified in the notice if that date is on or after the date of the determination, and otherwise from the beginning of the first new period of the tenancy that begins on or after the determination. Where either of those would cause the tenant undue hardship, the tribunal can direct a different date, but section 14ZB(4) requires it to fall within two months beginning with the date of the determination, so it is a narrow window rather than a two month extension.

If you are reading tribunal decisions to calibrate your own practice, and it is a good habit, check which regime each one was decided under before you draw a lesson from it.

The short version

On a private assured tenancy, the figure you propose is the best outcome available to you. The evidence behind it decides whether you keep it. And for the first six months of a tenancy, the rent you advertised is live too.

Worth knowing where your website's contribution to that figure actually comes from.