"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
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 12 months, 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.