Only 1,532 tenants in England applied to the tribunal for a rent determination across 2024 and 2025, according to Shelter's analysis. That was rational under the old rules: the tribunal could set your rent higher than your landlord had asked, and backdate it. Both of those risks were removed on 1 May 2026. The tribunal can now only confirm or reduce the figure on the notice, and it costs £47 to ask. If you have received a rent increase this month, the worst realistic outcome of a challenge is that you pay £47 and the rent goes up exactly as your landlord proposed, later than it otherwise would have.
What changed on 1 May 2026
Since 1 May 2026, a Section 13 notice served on the prescribed Form 4A is the only lawful way to raise rent on an assured tenancy in England. Trowers & Hamlins, summarising the commencement instruments, confirm that rent review clauses in existing tenancy agreements cannot be used for increases after that date, and that landlords cannot serve a Section 21 notice on or after 1 May 2026 even where the agreement says they can. Goodlord's guidance for agents puts it more bluntly for the industry: fixed-term renewals, rent review clauses and informal negotiations no longer work.
The mechanics that matter to you:
- One increase per 12 months. The clock runs from the date the last increase took effect, not the date the notice was served.
- Two months' notice minimum, up from one month under the old regime, whatever your payment period.
- The new rent must start on the first day of a rental period.
- No increase in the first 12 months of a tenancy.
- You apply on Form MR1, available on GOV.UK. Older guidance calls it Rents 1. Same form, renamed.
The fee framework came through the draft First-tier Tribunal (Property Chamber) Fees (Amendment) Order 2026, debated in the Commons on 27 April 2026. The justice minister Sarah Sackman confirmed a £47 application fee for appealing a rent increase with no hearing fee, against the previous £114 application fee and £227 hearing fee. She described it as "one of the lowest fees across HMCTS". Help with Fees applies if you cannot afford it.
One conflict worth flagging. Shelter's public-facing page still carried the old warning that the tribunal's rent "could be more than your landlord asked for", with a note that the guide was being updated for the new rules. The position under the Renters' Rights Act 2025, confirmed by both Shelter's own professional briefing and the commencement analysis from BCLP, is that the tribunal can confirm or reduce the proposed rent but cannot increase it. Go with the Act.
Why the London numbers favour the tenant
The tribunal's job is to decide the open market rent for your property in its actual condition. That is a question of local evidence, and London's evidence currently pulls in two directions.
The ONS Price Index of Private Rents, in its July 2026 release, put annual private rent inflation in London at 2.2% in the 12 months to June 2026, the lowest of any English region, against 6.3% in the North East and 3.3% across the UK. PIPR measures achieved rents on both new and existing tenancies, which is why the mayor's London Rents Map is built on it.
Rightmove measures something different. Its Q2 2026 tracker had average advertised rents in London up 2% over the quarter to a record £2,791 a month, with annual growth accelerating to 2.9%, the largest quarterly rise since 2023 and driven by inner London. Rightmove is explicit in its methodology that the tracker captures asking prices at the very beginning of the letting process.
So a letting agent can honestly say advertised rents in London have hit a record, while the ONS honestly says achieved rents in the capital are rising more slowly than anywhere else in England. Both are true. Only one of them is evidence of what your flat would actually let for, and it is not the asking price.
Two further pieces of context are useful in a bundle. Hamptons' December 2025 lettings index found the gap between new-let and renewal rents had narrowed to £61 a month across Great Britain, the smallest since July 2021, down from £170 at the October 2023 peak. And Hamptons' Aneisha Beveridge predicted in January 2026 that the ban on accepting offers above the advertised rent would itself "push up advertised rents", with tenants bidding below. If your landlord's comparables are all asking prices from portals, that prediction is your counter-argument.
Read the Form 4A before you read the number
Check the form before you check the figure. A defective notice does not raise your rent, and the Act also gives you a route to challenge a notice's validity at the tribunal, which the Ministry of Justice confirmed attracts the same £47 fee.
| What to check | Where it goes wrong |
|---|---|
| The form itself | Anything on the old Form 4, or an agent's own letterhead template, is not the prescribed form |
| Notice period | Fewer than two months between service and the start date |
| Start date | Not the first day of a rental period (if you pay on the 5th, a 1st-of-month start is wrong) |
| 12-month gap | Increase taking effect less than 52 weeks after the last one, counting from when the last one took effect |
| First-year bar | Any increase inside the first 12 months of the tenancy |
| Parties and address | Wrong landlord name, missing joint tenant, old flat number |
| Completeness | Blank mandatory fields, unsigned, undated |
Keep the envelope, the email header, the date stamp. If it arrived by email, check your agreement permits service by email.
Building borough-level comparables
Shelter's guide confirms the tribunal works from average rents for similar private properties in the local area, and that tenants can gather listing evidence from Rightmove, Zoopla and SpareRoom. Build the bundle over an evening or two:
- Six to ten comparables, same borough, same bedroom count, same property type. A one-bed conversion flat above a shop on Hoe Street is not a one-bed in a new block by the station. Screenshot each with the date visible and note the postcode.
- The mayor's London Rents Map borough figure for your bedroom count. It is ONS PIPR data, so it reflects achieved rents on new and existing tenancies, and it is updated monthly with the previous month's data. Print the page.
- Distance and transport, in real terms. Walthamstow Central on the Victoria line prices differently from a ten-minute bus ride away in Chingford, and the tribunal will accept that if you show it.
- Condition, honestly documented. Photographs of damp, single glazing, a boiler that has been "on the list" since March. The MR1 form asks who is responsible for repairs, and the tribunal can inspect if either side asks. Poor condition reduces market rent, and your EPC rating is part of that picture: energy performance rules give renters separate leverage worth knowing about.
- Your payment record. A clean two-year ledger is not legally decisive, but a landlord arguing top-of-market rent looks weaker when the tenant is faultless. If you pay through an app, export the history.
Cut anything that does not help. Six strong comparables beat thirty weak ones.
Two worked examples
The figures below are arithmetic on hypothetical tenancies, not market claims. Substitute your own numbers from the London Rents Map.
A Walthamstow one-bed. You pay £1,375. The Form 4A, served 1 July, proposes £1,550 from 1 September, a 12.7% rise. Your six comparables in E17 average £1,420. You apply on MR1 on 15 August, before the start date, and keep paying £1,375. The tribunal decides in November. Because increases can no longer be backdated, the three months of £175 differential you did not pay is money kept: £525 against a £47 fee. If the tribunal sets £1,420, you save a further £130 a month, roughly £1,560 over the following year.
A Clapham two-bed. You pay £2,100; the notice proposes £2,400 from 1 October. Lambeth comparables in SW4 support around £2,250. Even if the tribunal confirms nothing lower than £2,250, that is £150 a month, £1,800 a year, plus the months of delay. And if the tribunal decides your landlord was right at £2,400, it cannot go above £2,400. That asymmetry is the whole case for applying. Comparables in fashionable postcodes are often padded by refurbished stock; if you are comparing your flat to a rebuilt one, know what the local market actually offers at each price point.
Deadlines and cash flow
You must apply before the start date on the notice. Miss it and the increase takes effect automatically, with no late route in. Two months' notice means you have, in practice, about seven weeks of thinking time.
While the case is live, keep paying the old rent. That is the legal position, not a tactic. On timing, the new rent takes effect from the date in the notice only if that date falls on or after the determination date; otherwise it starts from the payment date after the decision, and the tribunal can push it back by up to two further months where paying immediately would cause undue hardship. There is often no hearing unless one side asks for one, and Shelter warns a decision can take a few months.
One caveat: the Act reserves a power for the government to reintroduce backdating by regulations if it concludes the no-backdating rule is being abused. That has not happened, but a weak, speculative application is no longer cost-free in the political sense.
What to say to the agent
Email, not phone. Something close to:
Thank you for the Section 13 notice dated [date]. Before the start date I intend to refer the proposed rent to the First-tier Tribunal on Form MR1 unless we can agree a figure. My comparable evidence for [borough], attached, supports around £X. I am content to agree £X in writing today and withdraw the referral.
That gives a managing agent a cheap way out. Their client faces a tribunal file, a possible inspection and a rent that cannot rise above what they already asked. Many will take £X.
The retaliation question
The old answer to "should I challenge?" was that a landlord could serve a Section 21 notice and have you out in two months without a reason. That answer is gone: Trowers & Hamlins confirm no Section 21 notice can be given on or after 1 May 2026, whatever the tenancy agreement says, and a landlord now needs a statutory ground for possession and, if you do not leave, a court.
Retaliation has not become impossible. It has become slow, evidenced and expensive, which is a different risk calculation from the one most London renters learned. Meanwhile you can end the tenancy yourself on two months' written notice, ending on a rent day or the day before.
Goodlord told its agent clients that 22% of tenants say they will always challenge an increase under the new powers. If that holds in London, the tribunal's borough-level comparable decisions will start doing quietly what no rent control bill managed: publishing what flats in E17 and SW4 are actually worth.