Rent increase letter vs Section 13 notice: what still works

The short answer

For a private assured periodic tenancy in England, a rent increase letter cannot put the rent up. Since 1 May 2026, the only way to increase the rent is a Section 13 notice on Form 4A. That is true even if your tenant has already agreed the new figure. Rent review clauses in tenancy agreements no longer work either.

A letter is still useful. You can use it to discuss the increase before you serve the notice, to send the notice with a clear explanation, and to record things that do not raise the rent. This guide explains the difference, with a worked example. It is general information for landlords in England, not legal advice.

What the law says now

Section 6 of the Renters’ Rights Act 2025 changed section 13 of the Housing Act 1988. For private assured tenancies, the rent for a period may not be higher than the rent for the previous period except by:

• a Section 13 notice, or an agreement after such a notice for a rent lower than the one proposed
• a decision of the First-tier Tribunal on the rent
• a written agreement, after a tribunal decision, for a rent lower than the tribunal’s figure

Any term of the tenancy that says the rent must or may go up in any other way has no effect. That catches rent review clauses, fixed annual uplifts and index-linked increases written into the agreement.

Government guidance puts it plainly: you need to follow the section 13 process every time you increase the rent, even if you have already agreed the increase with your tenants.

Rent increase letter vs Section 13 notice compared

What a letter can still do

A letter, email or conversation is still worth having. Government guidance says you should first discuss any rent increase with your tenant. A letter can:

• Warn the tenant early. Explain that you plan to propose a new rent, and why. This gives them time to plan.
• Set out your evidence. Share the comparable rents you looked at. A tenant who understands the figure may be less likely to refer it to the tribunal.
• Cover the notice. Send a short covering letter with your Form 4A. It must not contradict the notice, and it does not replace any part of it.
• Record an agreed lower rent. If, after your notice, you agree a rent lower than the one you proposed, put it in writing.
• Record a decision not to increase. You can agree in writing that the rent will stay the same.
• Reduce the rent. The Act does not stop you agreeing a lower rent. Only increases are restricted.

A letter cannot set a start date for a higher rent, add a “pet rent” or service charge to the rent, or raise the rent because the tenant has agreed.

Do rent review clauses still work?

No. Government guidance says rent review clauses are not valid for private tenancies from 1 May 2026. If an increase under a rent review clause was agreed before 1 May 2026 but takes effect after that date, the increase does not apply.

If a rent review clause increase took effect before 1 May 2026, it still counts. Under the transitional rules, your next increase on Form 4A cannot take effect until 52 weeks after it. For example, if a clause increased the rent from 1 March 2026, 52 weeks later is Sunday 28 February 2027, so the next increase on a tenancy with rent due on the 1st can start on Monday 1 March 2027 at the earliest.

What about an agreement after a Section 13 notice?

Once you have served Form 4A, you and your tenant can agree a different outcome. Form 4A tells the tenant they can agree with you, in writing, to change or delay the increase. Under the amended section 13, an agreed figure must be lower than the rent you proposed. You cannot use the agreement to push the rent higher than your notice.

If your tenant refers the notice to the tribunal, the tenant will not pay more than the rent you proposed. See what happens if a tenant challenges a rent increase.

Worked example: an agreed increase that needs a notice

• The tenancy began on Thursday 1 January 2026. Rent is £1,000 a month, due on the 1st.
• There has been no increase.
• On Monday 12 October 2026, the tenant emails to agree a new rent of £1,040 “from 1 December 2026”.

That email does not change the rent. Two rules also stop 1 December 2026 being used:

• The first increase cannot start until 52 weeks after the tenancy began.
• Even if it could, a notice served now would not give two months’ notice before 1 December.

You hand Form 4A to the tenant on Monday 19 October 2026, proposing £1,040.

So question 4.6 reads 1 January 2027. With the notice, send a short letter thanking the tenant for agreeing, and explaining that the law requires the formal notice. Because the tenant has agreed, a tribunal referral is unlikely, but they keep the right to make one before 1 January 2027.

Our free rent increase date calculator runs the same checks.

Common mistakes

• Relying on an email or signed letter. An agreed increase still needs Form 4A.
• Relying on a rent review clause. It has no effect for increases taking effect from 1 May 2026.
• Asking the tenant to sign a new agreement at a higher rent. A term that raises the rent outside section 13 has no effect.
• Treating unpaid “agreed” increases as arrears. If the rent was never validly increased, the tenant owes the old rent.
• A covering letter that conflicts with the notice. Keep the dates and figures identical.

Frequently asked questions

My tenant is happy to pay more. Why do I need a notice?

Because the law now says the rent can only go up through section 13. Government guidance says to follow the process even if the increase is already agreed.

Can I use Form 4 instead?

No. Form 4 is for social housing. Private landlords use Form 4A. See Form 4 vs Form 4A.

Can I give more than two months’ notice?

Yes. Two months is the minimum. Any later date must still be the first day of a rent period.

What if I already collected a higher rent based on a letter?

Take advice. A rent increase that did not go through section 13 has no legal effect for private assured tenancies.

Can I put the rent down by letter?

Yes. Nothing in section 13 stops you agreeing a lower rent. Put it in writing and keep a copy.

What if my notice had a mistake?

See what to do if a Section 13 notice was served on the wrong form.

Next steps

• Create your notice on the Section 13 notice (Form 4A) page. It checks your dates before you download.
• Read how to fill in Form 4A, question by question.
• See more date scenarios in how to work out the earliest rent increase date.

If you are in a dispute about a rent increase, speak to a solicitor; tenants can get advice from Shelter.