Rent Increase Letter vs Section 13 Notice: Which Do You Need?

If you are weighing up a rent increase letter against a formal Section 13 notice, the honest answer for England landlords in 2026 is that the two are not interchangeable, and getting the choice wrong can cost you the entire increase. Since the Renters’ Rights Act 2025’s tenancy reforms came into force on 1 May 2026, the rules on how, when and how often you can raise the rent have tightened considerably. A friendly letter still has its place, but it can no longer do the heavy legal lifting on its own. This guide explains what a plain letter can still do, why every increase now needs the prescribed statutory form, and how to combine the two so your increase actually sticks.

The short answer

For an assured periodic tenancy in England, which, post-Renters’ Rights Act, is now every assured tenancy, there is only one legally binding route to raise the rent, whether or not the tenant agrees: serving the current prescribed Section 13 form on GOV.UK (Form 4A). A “rent increase letter” written in your own words has no statutory force, and since 1 May 2026 it cannot raise the rent even if the tenant signs to agree the new figure.

So the distinction comes down to what each document does:

• A letter explains your proposal and can record that the tenant is happy with it, but it does not change the rent. GOV.UK says you need to follow the Section 13 process every time you increase the rent, even if you have already agreed the increase with your tenant.
• The statutory Section 13 procedure on the prescribed form is what actually raises the rent, whether or not the tenant agrees. A letter alone will not bind them.

The rest of this guide unpacks what that means in practice, because the detail is where landlords slip up.

Why the rules changed in 2026

Before the Renters’ Rights Act, many tenancies were assured shorthold tenancies (ASTs) with fixed terms, and rent-review clauses were common, a clause might say “rent increases by 4% each year” or “rent rises in line with RPI.” Landlords often relied on those clauses, or on Section 21 as a backstop to remove a tenant who refused an increase.

That world is gone. As of 1 May 2026:

• Section 21 is abolished. There is no “no-fault” eviction to fall back on if a tenant resists a rise.
• All assured tenancies are periodic. Fixed terms are abolished, so there is no longer a fixed-term rent-review clause to invoke. See our guide to what a periodic tenancy is for the full picture.
• Rent-review clauses are banned. A tenancy agreement can no longer contain a clause that sets out automatic or formula-based increases. Any such clause is unenforceable.
• Section 13 is the only mechanism for any rent increase, agreed or not, and it can be used only once in any 12-month period.

Because the contractual shortcuts have been removed, the prescribed Section 13 form is now required for every rent increase, including one the tenant freely agrees to.

What is a rent increase letter?

A rent increase letter is simply a written communication from you to your tenant proposing a new rent. It is not a defined legal instrument. It might say something like: “From 1 September your rent will be £1,150 per month, please let me know if you are happy to continue on that basis.”

There are two scenarios where a letter is genuinely useful:

1. Agreeing the figure first. If you and the tenant discuss the rent and they are willing to pay more, perhaps after you have improved the property, or simply as a sensible negotiated step, a letter confirms what you have discussed. It does not change the rent on its own, though: since 1 May 2026 the rent can only go up through a Section 13 notice or a tribunal determination, so you still serve the prescribed form with at least two months’ notice.
2. As a courteous heads-up before the formal notice. Many good landlords send a plain-English letter first, explaining why an increase is coming and what the new figure will be, then follow it with the prescribed form. The letter manages the relationship; the form does the legal work.

What a letter cannot do is put the rent up, whether or not the tenant agrees. If you write “your rent is now £1,150” and the tenant ignores it, objects or even agrees, you have no enforceable increase. You would still need to serve the prescribed Section 13 form to make it bite.

What is a Section 13 notice?

A Section 13 notice is the statutory route under section 13 of the Housing Act 1988 for a landlord to propose a new rent on a periodic assured tenancy. It must be given on the current prescribed Section 13 form on GOV.UK, not a letter of your own design, and not an old template you downloaded years ago.

The key features in 2026 are:

• Once a year only. The new rent cannot take effect earlier than 52 weeks after the tenancy began or, after that, 52 weeks after the last increase took effect, so in practice there is one increase a year.
• Minimum notice period. The notice (Form 4A) must give the tenant at least two months’ notice before the new rent takes effect, whatever the rent period, and the new rent must start at the beginning of a period of the tenancy.
• Tenant’s right to challenge. The tenant can refer the proposed rent to the First-tier Tribunal (Property Chamber) before the increase date. Crucially, since the Renters’ Rights Act, the tribunal cannot set the rent higher than the figure you proposed, it can only confirm your figure or set a lower, market-justified one. That change removes the old deterrent where tenants risked the tribunal raising the rent above the landlord’s proposal.
• Effective date. If the tenant does not refer the notice to the tribunal, the new rent takes effect from the date stated in the notice, provided the form was valid and properly served. If they do refer it, there is no backdating: the rent the tribunal sets starts on the date in your notice only if the decision comes first; otherwise it starts at the beginning of the first rent period beginning on or after the decision, or on a date the tribunal directs (within two months of the decision) if paying sooner would cause the tenant undue hardship.

If any of these requirements is missed, the notice can be invalid, and an invalid notice means no lawful increase. We cover the specific failure points in invalid Section 13 rent increases.

Side-by-side comparison

Feature	Rent increase letter	Section 13 notice
Legal status	Courtesy only; cannot raise the rent, even with consent	Statutory procedure under Housing Act 1988 s.13
Binds a tenant who has not agreed?	No	Yes (if valid)
Prescribed form required?	No	Yes, current prescribed form on GOV.UK
Frequency limit	N/A (a letter cannot raise the rent)	Once per 12 months
Tenant can challenge at tribunal?	N/A (no increase to challenge)	Yes, before the increase date
Tribunal can raise above your figure?	N/A	No, it can only confirm or reduce
Best used for	Courtesy heads-up and discussion before serving	Every lawful increase, agreed or not
Risk if done wrong	Tenant simply keeps paying the old rent	Increase void; serve a fresh valid notice with another two months’ notice

A worked example

Scenario. Priya lets a two-bedroom flat in Leeds on an assured periodic tenancy. The rent is £950 per month. Local rents have risen and she wants to move to £1,025 from 1 September 2026. Her last increase took effect on 1 August 2025.

Step 1, Check the 12-month rule. Her last lawful increase was 1 August 2025. A new Section 13 increase taking effect on 1 September 2026 is more than 12 months later, so the timing is clear.

Step 2, Decide the route. Priya first sends a short, friendly rent increase letter explaining that local rents have risen, the property is in good order, and she proposes £1,025 from 1 September. She invites the tenant to agree.

• If the tenant agrees in writing, that is a good start, but the letter and the tenant’s acceptance do not change the rent on their own. Priya must still serve the current prescribed Section 13 form on GOV.UK, proposing £1,025 and giving at least two months’ notice before 1 September.
• If the tenant does not respond, or objects, the letter alone achieves nothing either. The same prescribed form, with at least two months’ notice before 1 September, is what makes the increase bind.

Step 3, Serve correctly. Priya completes the prescribed form in full, states the new rent and the date it takes effect (1 September 2026), and serves it in line with the tenancy agreement’s service rules, keeping proof of service.

Step 4, The tenant’s options. The tenant can accept the new rent (by paying it or doing nothing to challenge) or refer it to the First-tier Tribunal before 1 September. If they refer it, the tribunal will assess the open-market rent. Because it cannot exceed £1,025, Priya’s proposed figure, her downside is capped: the worst case is that the tribunal confirms £1,025 or sets something lower if £1,025 is above market. A referral can delay the increase, though: if the tribunal decides after 1 September, the new rent starts only from the beginning of the first rent period beginning on or after its decision (no backdating), or from a date within two months of the decision if the tribunal finds paying sooner would cause the tenant undue hardship.

Outcome. Priya’s increase is made lawful by the prescribed form whether or not the tenant agreed, the letter keeps the relationship on track, and she has documented the whole process. To sanity-check her figure she could use a free rent increase calculator before sending anything.

Why a letter alone is no longer enough

Before 1 May 2026, a tenant’s express agreement to a higher rent, recorded in a letter or a signed variation, was binding as a matter of contract without any Section 13 notice. That route has closed. Section 13(4A) of the Housing Act 1988, as amended by the Renters’ Rights Act, says the rent for a period cannot be greater than the rent for the previous period except by a Section 13 notice (or an agreement following one) or a tribunal determination, and any other provision for a higher rent has no effect. GOV.UK guidance confirms you must follow the Section 13 process every time you increase the rent, even if you have already agreed the increase with your tenant.

A letter, or a short note both of you sign and date, is still worth having: it shows the tenant is on board and makes a later dispute or tribunal referral less likely. A vague verbal “yeah, that’s fine” is hard to evidence if the relationship sours. But in every case it is the prescribed form, served with at least two months’ notice, that makes the new rent payable.

When you must use the prescribed Section 13 form

Use the prescribed form for every increase, including when:

• The tenant has not agreed to the increase;
• The tenant has agreed to the increase, because an agreement alone cannot raise the rent; and
• You may need to rely on the increase in any later possession or arrears proceedings.

Because rent-review clauses are banned and Section 21 is gone, the prescribed form is now the workhorse of rent increases. Every landlord who increases rent must use it, with letters reserved for the friendly cover note. For the full mechanics, see Section 13 rent increases explained and the step-by-step guide to increasing rent legally.

Common mistakes that void an increase

Even landlords who reach for the right document trip over the detail. Watch for these:

Using an old or self-made form

Only the current prescribed Section 13 form on GOV.UK is valid. A form you saved a couple of years ago may be out of date, and a letter dressed up to look official is not a substitute. Always download the current version at the time you serve.

Increasing more than once in 12 months

You cannot stack increases. A Section 13 notice proposing a new rent that would take effect earlier than 52 weeks after the last increase took effect (or, for a first increase, 52 weeks after the tenancy began) is invalid. Plan your timing so each increase is at least 12 months after the last.

Getting the notice period or effective date wrong

If the date the new rent is meant to start does not give the tenant at least two months’ notice, or does not fall at the beginning of a period of the tenancy, the notice fails. Count carefully from the date of service.

Treating silence as agreement on a letter

If you only sent a letter, you do not have an increase, whether the tenant said nothing or said yes. You have nothing. Silence on a letter is not consent, and even written consent to a letter is not a Section 13 notice.

Trying to rely on a rent-review clause

Any automatic-increase or formula clause in the agreement is unenforceable post-Renters’ Rights Act. Ignore it and use Section 13.

A pre-send run-through against our rent increase compliance checklist catches most of these before they cost you months of higher rent.

Frequently asked questions

Can I just send a letter saying the rent is going up?

You can send the letter, but it does not create a binding increase on its own, even if the tenant agrees to it. You must serve the current prescribed Section 13 form on GOV.UK, giving at least two months’ notice, for the increase to take effect lawfully.

Is a rent increase letter ever legally binding?

Not on its own since 1 May 2026. Under section 13(4A) of the Housing Act 1988, a higher rent has no effect unless it comes through a Section 13 notice (or an agreement following one) or a tribunal determination, and GOV.UK says the process applies even where the increase is already agreed. A letter is useful to explain the figure and record the tenant’s agreement, but you must serve the prescribed form as well.

How often can I increase the rent?

Through the statutory route, no more than once in any 12-month period using a valid Section 13 notice. Since 1 May 2026 an increase the tenant agrees to still has to go through Section 13, so the same once-a-year limit applies to it, and most landlords align increases to an annual cycle.

Can the tribunal raise my rent above what I asked for?

No. Since the Renters’ Rights Act 2025, if a tenant refers your Section 13 proposal to the First-tier Tribunal, the tribunal cannot set a rent higher than the figure you proposed. It can confirm your figure or set a lower, market-justified one, so your proposed rent is effectively the ceiling for that round.

Do I still need a Section 13 notice if my tenancy agreement has a rent-review clause?

Yes. Rent-review clauses are banned and unenforceable under the Renters’ Rights Act. You cannot rely on the clause, so any increase must go through the Section 13 process on the prescribed form, even one the tenant agrees to.

What happens if my Section 13 notice is invalid?

An invalid notice produces no lawful increase, and you have to serve a fresh valid notice, giving at least two months’ notice again and a start date that meets the once-a-year rule, so you can lose months of higher rent. Common causes are using an out-of-date form, breaching the once-a-year rule, or getting the effective date wrong. See our guide to invalid Section 13 rent increases.

Bringing it together

The practical takeaway is simple. A rent increase letter is a relationship tool: use it to propose a figure, explain your reasons and gauge the tenant’s reaction. The prescribed Section 13 notice is the legal tool: use it for every increase, whether or not the tenant has agreed. Many of the best landlords use both, a courteous letter first, then the prescribed form to make it binding, and they diary the 12-month cycle so they never serve too soon. For the exact wording, see our Section 13 rent increase template.

Coming soon

Tenancy Pilot is launching soon, and its rent increase notice generator is built precisely for the choice this guide describes. It will help you draft a clear cover letter, produce a compliant notice aligned to the current prescribed form, check your 12-month timing automatically, and store proof of service, all from one command centre with deadline alerts so you never serve too early. Want it the moment it goes live? Join the waitlist and be first to use the rent increase tools.

This guide is general information for England landlords, not legal advice. Rules change and individual circumstances vary. Always check the current position on GOV.UK and legislation.gov.uk, use the current prescribed forms, and consult a qualified solicitor before acting.