"How much can I put the rent up by?" has a frustrating two-part answer. There is no fixed percentage cap — no rule that says you cannot go above 5% or 10%. But there is a real ceiling, and it is enforced by the tenant’s right to challenge: the increase has to be to a market rent, and if you overreach, a tribunal can knock it back.
Since the Renters’ Rights Act, this all runs through one route, once a year. Here is how it actually works, and how to set an increase that sticks.
This is general guidance, not legal advice.
The short version
For a periodic assured tenancy, which, since 1 May 2026, is every new tenancy — a rent increase must go through a Section 13 notice. Three rules define it:
There is no percentage cap inside those rules. But "market rent" is the cap in disguise, because the tenant can dispute it.
Why there is no percentage limit, and why that is not a loophole
People expect a number, like "you can only go up 3%". There is not one, and there was never going to be one, because a fixed cap would punish landlords who kept rents low for years and reward those who ratcheted them up annually. Instead the test is the market: you can move the rent to what the property is genuinely worth now, in one step, even if that is a large jump because you have not raised it in a while.
The catch is that you have to be right about the market. Set it at or below what comparable local properties actually let for and it will hold. Set it above — using the increase as a way to force the tenant out, or just chancing it, and you have handed them a winnable challenge.
The tenant can challenge it, and the tribunal cannot make it worse for them
This is the part that changed, and it matters. A tenant who thinks a Section 13 increase is above market rent can refer it to the First-tier Tribunal, free. The tribunal looks at comparable local rents and decides the market figure.
Under the Renters’ Rights Act, two things protect the tenant here:
So an over-ambitious increase does not just risk being reduced to market — it invites a challenge the tenant now has nothing to lose by bringing. Pitching it right the first time is the whole game.
How to set an increase that holds
How LetCompliance helps: the Section 13 rent increase tool works out the earliest lawful date and the two-month notice, generates the notice on the correct prescribed form, and keeps the once-a-year gap for you, so the increase is procedurally bullet-proof and you are only ever arguing about the figure, not the paperwork.
Sources
The paperwork: get this wrong and there is no increase
The amount is a judgement call. The mechanism is not, and a defective notice means the old rent simply continues.
Use the right form. Private landlords serve a Section 13 notice on Form 4A: there is a field-by-field walkthrough here. Form 4 is the social-sector version. This is not a formatting preference — the wrong form is a defective notice.
Once every 52 weeks. Serving eleven months after the last increase voids it.
At least two months' notice, and allow extra time if you post it rather than deliver it by hand, because of the deemed service rules.
Starting at the beginning of a rental period. If rent falls due on the 8th, the new rent starts on an 8th.
Served on every tenant, not just the one who answers your messages. Keep proof of how and when.
And a text message agreeing a figure is not a Section 13 notice. If the tenant later disputes it, you have nothing statutory to fall back on and no increase.
A worked example, both ways
Daniel lets a two-bed terrace at £950. Comparable properties nearby are letting at £1,075 to £1,125. He last increased the rent nineteen months ago.
He serves Form 4A on 4 March proposing £1,075 from 6 May, keeps four dated portal comparables in the property file, and includes two lines explaining the figure and noting that it sits at the bottom of the local range.
If the tenant accepts, the rent is £1,075 from 6 May. The step that actually completes it is updating the standing order or Direct Debit mandate — a surprising number of agreed increases quietly fail because nobody changed the payment instruction.
If the tenant refers it to the tribunal, Daniel submits the comparables. Say the tribunal determines £1,050. That becomes the rent, from the date the tribunal sets rather than backdated to 6 May. He is £25 a month below his proposal, with a figure that is now independently justified and a tenant who was treated reasonably.
Now the alternative. Had he proposed £1,250 with nothing to support it, the likely outcome is a similar £1,050, but two months later, without backdating, and with a tenant who has spent the intervening period deciding whether to stay. The aggressive figure earns nothing and costs the relationship.
Judging the number itself
Since there is no percentage cap, the real question is what an increase is worth against what it risks.
Price against lettings, not asking prices. Portal listings are what landlords hope for. What you want is what comparable properties actually let for, and how quickly they went.
Compare like for like. Same number of bedrooms, similar condition, similar EPC, and the same furnished or unfurnished basis. A refurbished flat two streets away is not your comparable.
Set the increase against the cost of losing the tenant. A four-week void on a £950 flat costs roughly £950 in rent, plus council tax now falling on you, cleaning, advertising and referencing — realistically £1,400 to £1,800, before you count the risk that the replacement is worse. Against that, taking £25 a month less than the top of the range costs £300 a year. Landlords lose good tenants over sums smaller than the void that follows.
Small and regular beats large and rare. £25 a year reads as normal. Nothing for three years followed by £150 reads as a betrayal, and it is the single most common reason a good tenancy ends.
Remember the tax side. From April 2027 property income is taxed two points higher — 22, 42 and 47 per cent, so a higher-rate landlord keeps 58p of each extra pound, not 60p. It does not change the decision, but it should temper the idea that an aggressive increase is free money.
The part that usually gets forgotten: an agreed increase only happens if the payment instruction changes. LetCompliance generates the Form 4A, checks the timing, records service, then updates the rent ledger and the Direct Debit mandate. First property free.
Section 21 → Section 8 Transition Map (2026)
Section 21 was abolished on 1 May 2026. Map every active S21 / Form 6A scenario onto a valid Section 8 ground with this 2-page transition guide.
- Pre-1 May 2026 Form 6A — still valid? Decision tree
- Map every S21 trigger to a Section 8 mandatory / discretionary ground
- Ground 8 (rent arrears) — 13-week threshold under RRA 2025
- Top 5 evidence packs courts now expect for possession
Frequently asked questions
How much can a landlord increase rent in 2026?
There is no percentage cap. Since the Renters’ Rights Act a rent increase runs through a Section 13 notice, once every 52 weeks, with two months’ notice, and must be to a market rent — broadly what the property would let for today if newly on the market. You can move to market rent in one step even if that is a large jump, but you cannot go above market rent, because the tenant can challenge it.
Can a tenant challenge a rent increase?
Yes, free, at the First-tier Tribunal, which decides the market rent from comparable local rents. Under the Renters’ Rights Act the tribunal cannot set the rent higher than the landlord proposed, and cannot set it above market rent. Because the worst case for a tenant is now that the tribunal simply agrees with the landlord, there is far less reason for them not to challenge an over-ambitious increase — so pitching it right first time matters.
How do I make a rent increase that holds up?
Research genuine comparables (similar size, condition and area, advertised or let now) and keep a note of them as evidence; price to market rent for the property as it actually is; and use the correct Section 13 process — right prescribed form, two months’ notice, not more than once a year. A defective notice can make the increase unenforceable, and a guarantor is not liable for an increase that was not lawfully imposed.