Index-linked or CPI rent review clause after 1 May 2026: the tenant refusal walkthrough
Plenty of older tenancy agreements contain a clause that lets the landlord raise the rent automatically each year by inflation, often pegged to CPI or RPI. Since 1 May 2026 those clauses can no longer be used: every rent increase on a tenancy now has to go through the statutory Section 13 process, and a contractual review clause cannot override it. This walkthrough explains why an index-linked uplift is no longer enforceable, how to spot when a landlord is trying to apply one anyway, and gives you a template letter to refuse it calmly and correctly.
Plenty of tenancy agreements signed before the reforms contain a clause that lets the landlord raise the rent automatically each year. Sometimes it is a flat percentage; very often it is pegged to inflation, expressed as CPI (the Consumer Prices Index) or the older RPI (the Retail Prices Index). For years these clauses simply operated in the background, and the rent went up on the anniversary without anyone serving a notice.
Since 1 May 2026 that no longer works. The reforms route every rent increase on an assured tenancy through one statutory channel: the Section 13 process, served on the prescribed Form 4A, with at least two months' notice and a right for you to challenge the proposed figure at the First-tier Tribunal. A contractual rent review clause cannot be used to sidestep that. This walkthrough explains why, how to recognise when a landlord is trying to apply an index-linked uplift anyway, and gives you a calm, correct template to refuse it.
Why the clause no longer works
The purpose of the post-May-2026 rules is simple: every tenant should get proper notice of an increase and a genuine chance to challenge it. An automatic review clause delivers neither. It changes the rent without notice and without any route to the tribunal, which is exactly what the reforms set out to stop.
So the law now provides that increasing the rent on an assured tenancy has to be done through Section 13. A clause that tries to raise the rent by some other mechanism, including an inflation index, cannot be relied on for that purpose. The words may still sit in your signed agreement, but they have no legal effect when it comes to pushing the rent up. If the landlord wants more rent, they have to serve a valid Form 4A, and you keep every protection that comes with it.
What an index-linked clause usually looks like
You will normally find it in the rent section of the agreement. The common forms are:
- "The rent shall increase on each anniversary of the tenancy by the percentage increase in the Consumer Prices Index over the preceding twelve months."
- "The annual rent will be reviewed each year and increased in line with RPI."
- "The rent shall rise by the greater of 3% or CPI on each review date."
All of these are review clauses. None of them can now be used to increase your rent. The "greater of" version is a particular favourite because it guarantees the landlord a rise even when inflation is low, but it is no more enforceable than the others.
How to spot a landlord trying to apply one
The tell-tale sign is an increase that arrives without the prescribed form. You might get an email or a letter that says something like, "As per clause 4.2 of your agreement, your rent will increase by 4.1% (CPI) from next month." There is no Form 4A, no two-month notice period framed as a statutory notice, and no mention of your right to go to the tribunal. That is a landlord relying on the old review-clause habit, and it is the situation this walkthrough is written for.
If instead you receive a properly completed Form 4A, that is the statutory route, and a different walkthrough applies: you would then be deciding whether the proposed rent is above the market level and whether to refer it to the tribunal.
What to do, step by step
1. Keep paying the rent you already pay. Do not pay the increased figure. Because the uplift was not lawfully imposed, the extra is not lawfully due, so paying only the existing rent does not put you in arrears. This protects you completely as long as you keep it up.
2. Write to the landlord promptly. A short, polite letter that sets out the position is almost always enough. You are not picking a fight; you are pointing out the correct procedure.
3. Invite them to use Section 13 if they want to propose a new rent. This keeps you reasonable and on solid ground. You are not refusing all increases forever, just this unlawful method of imposing one.
4. Keep records. Save the landlord's message, your reply, and your rent payment records. If the dispute escalates, this is your evidence that you behaved correctly throughout.
Template letter: refusing an index-linked increase
Dear [landlord or agent name],
Thank you for your message of [date] about increasing my rent at [property address].
The increase you have described relies on the rent review clause in my tenancy agreement [clause reference, if known]. Since 1 May 2026, the only lawful way to increase the rent on an assured tenancy in England is the statutory process under Section 13 of the Housing Act 1988, using the prescribed Form 4A and giving at least two months' notice. A contractual rent review clause, including one linked to CPI or RPI, can no longer be used to increase the rent.
I am therefore unable to treat the proposed increase as effective, and I will continue to pay my current lawful rent of [amount] per [period]. If you wish to propose a new rent, please serve a valid Form 4A and I will consider it, including my right to refer the proposed rent to the First-tier Tribunal.
I would be grateful for your confirmation that my rent remains at [amount] for now. Please treat this letter as a record of our correspondence on this point.
Yours sincerely, [Your name]
Adapt the bracketed details to your situation. Keep the tone measured: the aim is to resolve this without conflict, and most landlords accept the position once it is set out clearly.
If you have already paid an index-linked rise
If a review-clause increase was applied on or after 1 May 2026 and you paid it, the increase was not lawfully imposed and you can ask the landlord to reset the rent and credit or refund the overpayment. Use the same template, adding a line that you have overpaid since [date] and asking for the difference to be credited against future rent or refunded. Keep paying the original lawful rent going forward so the position stays clean.
Where this fits
This is one of a family of walkthroughs about getting the rent right under the new rules. If you have instead received a proper Form 4A and want to know whether the proposed rent is too high, our market-comparison and tribunal-evidence guides cover that. If your agreement still describes a fixed term, check whether it has converted to a periodic assured tenancy under the reforms. The thread running through all of them is the same: after 1 May 2026, no rent increase is lawful unless it comes through Section 13, and you always keep the right to challenge it.
If you are unsure whether a notice you have received is a valid Form 4A or just a dressed-up review-clause demand, that is exactly the kind of check RentSOS is built for: enter the details and we will tell you whether the increase has to be taken seriously, and if there are grounds to challenge it, give you the letter and tribunal templates to do so.
Frequently Asked Questions
+Can my landlord still use a CPI or index-linked rent review clause after 1 May 2026?
No. Since 1 May 2026 the only lawful way to increase the rent on an assured tenancy in England is the statutory Section 13 process, using the prescribed Form 4A and giving at least two months' notice. A clause in your tenancy agreement that says the rent rises automatically each year, whether by a fixed percentage or pegged to an index such as CPI or RPI, can no longer be used to push the rent up. The clause does not vanish from the paper version of your agreement, but it has no legal effect for increasing your rent. If the landlord wants more rent, they must serve a valid Form 4A and you keep the right to challenge it at the First-tier Tribunal.
+What is the difference between a Section 13 notice and a rent review clause?
A Section 13 notice is the statutory route: the landlord serves the prescribed form, gives proper notice, and you can refer the proposed rent to the tribunal if you think it is above the market level. A rent review clause is a term written into the tenancy agreement that tries to change the rent automatically without any of those protections, often once a year by an inflation index. The whole point of the post-May-2026 rules is to channel every increase through Section 13 so that tenants always get the notice period and the right to challenge. That is why contractual review clauses no longer bite.
+What should I do if I have already paid an index-linked increase?
If the increase was applied through a review clause rather than a valid Form 4A on or after 1 May 2026, the increase was not lawfully imposed, and you have a basis to ask the landlord to correct the rent and to credit or refund any overpayment. Write to the landlord setting out that the clause cannot be used and that no valid Section 13 notice was served, and ask them to reset the rent to the previous lawful figure. Keep paying the original lawful rent in the meantime so that no arrears can be alleged against you. If the landlord refuses, the dispute over what rent is lawfully due can be resolved through the courts, but most landlords correct it once the position is explained.
+Does this apply to a fixed-term tenancy or only a periodic one?
From 1 May 2026 the reforms convert most assured shorthold tenancies into periodic assured tenancies, and the Section 13 route is the mechanism for increasing rent on them. The key point is the same in both cases: an automatic contractual uplift cannot be used to raise the rent, and any increase must come through Form 4A. If your agreement still describes a fixed term, check whether it has been converted under the new rules; either way, an index-linked review clause is not a lawful way to increase your rent now.
+Can the landlord evict me for refusing an index-linked increase?
Refusing to pay an increase that was not lawfully imposed does not put you in arrears, because the extra amount is not lawfully due. As long as you keep paying the original lawful rent, you are not in breach. A landlord who tried to take action purely because you declined an unenforceable clause, or because you exercised your right to insist on the proper Section 13 process, would be on weak ground, and retaliatory action linked to a tenant asserting their rights is treated seriously. Always keep paying the rent you accept is due and keep a written record of the dispute.
+What if my agreement has both a review clause and mentions Section 13?
Some agreements mention both. It makes no difference to the outcome: the review clause cannot be used to increase the rent, and the landlord must still serve a valid Form 4A to do so. If the landlord points to the clause as authority for an automatic rise, you can reply that the clause has no effect for that purpose after 1 May 2026 and that you await a properly served Section 13 notice if they wish to propose a new rent. That keeps you firmly on the correct procedural footing.
Check your rent increase
Find out if your landlord’s Section 13 notice is valid. Free, anonymous, takes 2 minutes.
Free to check · £14.99 only if we find grounds
Keep reading
Related guides on tenant rights and rent increases.
Is my landlord raising the rent just to force me out? What the law actually allows
A large rent increase can feel like a quiet eviction, especially now that no-fault eviction is gone. But a Section 13 must reflect genuine market rent, not what would make you leave. Here is where you stand.
I already started paying the higher rent: can I still challenge it or get it back?
Paying the new rent for a few months does not automatically lock you into it. Whether you can still challenge or reclaim depends on two separate questions, and this walkthrough explains both.
The tribunal set my rent between what I pay now and what my landlord asked: did I still win?
Winning a rent challenge rarely means the rent stays frozen. It usually means the tribunal sets a fair figure below what your landlord asked. Here is how to work out what you actually saved.
Your landlord did up the flat and now wants a big rent rise: can you still challenge it?
A new kitchen or bathroom lets a landlord ask for more, but not for any figure they like. Here is how to tell a fair improved-market rent from an overreach, and when you can still challenge.
If I challenge my rent increase, will my landlord just try again next year?
Worried that challenging your rent increase just delays the next one? Here is what stops your landlord raising the rent again, why a successful challenge lowers your baseline for good, and why challenging is still worth it.
Your Section 13 notice went to the wrong address: were you validly served?
Your landlord sent the rent increase notice to an old or wrong address and you never received it. Here is when you are treated as served, when a wrong-address notice can be challenged, and what to do about it.