Top 10 Mistakes Landlords Make Before Serving a Section 21 Notice

Serving a Section 21 Notice (Form 6A) is one of the most common routes landlords take to regain possession of a property. On the surface, it seems straightforward — but in reality, even minor administrative errors can make the notice invalid.

Every week, courts strike out claims because landlords miss small but crucial compliance steps. Here are the 10 most common mistakes landlords make before serving a Section 21 notice — and how to avoid them.

1. Failing to Protect the Deposit Properly

Under the Housing Act 2004, any tenancy deposit taken must be protected in a government-approved scheme (DPS, TDS, or MyDeposits) within 30 days of receipt. The landlord must also give the tenant the Prescribed Information and the scheme’s Deposit Protection Certificate within the same 30-day window.

Many landlords either protect the deposit late, forget to serve the prescribed information, or fail to provide it in the correct format. Others change schemes mid-tenancy and forget to reissue the paperwork.

If these requirements aren’t met, any Section 21 notice served is automatically invalid, and the tenant can claim 1–3 times the deposit in compensation.

2. Not Providing a Valid Gas Safety Certificate

Regulation 36 of the Gas Safety (Installation and Use) Regulations 1998 requires landlords to provide tenants with a valid Gas Safety Certificate before they move in and to renew it every 12 months.

A common mistake is obtaining the certificate after the tenancy has already started — but by then it’s too late. The courts have repeatedly ruled that if a gas certificate wasn’t given before occupation, a landlord can lose the right to serve a Section 21 notice for the life of that tenancy.

Another oversight is failing to give tenants copies of subsequent annual certificates, which can also invalidate notice.

3. Forgetting the Energy Performance Certificate (EPC)

An EPC must be given to the tenant at the start of the tenancy. The EPC shows how energy-efficient the property is and is a legal requirement under the Energy Performance of Buildings Regulations 2012.

Many landlords assume that simply having an EPC on file is enough — it’s not. It must be served on the tenant before or at the start of the tenancy. If it’s missing or was only given verbally, your Section 21 cannot be relied upon until it’s properly provided.

4. Not Giving the Correct “How to Rent” Guide

Landlords must serve the most recent version of the government’s “How to Rent: The Checklist for Renting in England” guide when the tenancy starts (and again when it renews). It can be served in hard copy or electronically.

Some landlords use an old version or forget to issue it altogether. The guide is regularly updated, and using an outdated copy means your Section 21 notice is invalid. The safest approach is to download the current version from GOV.UK on the exact day the tenancy begins.

5. Serving the Notice Too Early

Section 21 cannot be served within the first four months of the original tenancy. Even if the tenancy becomes periodic, the clock starts from the original commencement date.

Landlords sometimes serve notice at month three to “get ahead,” or miscalculate when the tenancy started (especially where there’s a delay between signing and moving in). Serving too early renders the notice void, and it must be reissued later — wasting time and money.

6. Using the Wrong Form or Miscalculating the Dates

All Section 21 notices must be served using the prescribed Form 6A. The notice must give at least two clear months’ notice, and the end date must not fall before the end of a fixed term unless the agreement allows it. Landlords often:

• Use old versions of Form 6A.
• Miscalculate the expiry date (e.g., giving notice that ends a day too soon).
• Forget to allow for delivery time if posting or emailing.

If the tenant receives the notice late, the two-month clock starts from the day they receive it — not the day it was sent. Getting the dates wrong is one of the top reasons possession claims are dismissed.

7. Not Having the Correct Property Licence

Properties that meet certain criteria require a licence — such as HMO licences or selective licences under the Housing Act 2004.Landlords often assume their property doesn’t need a licence, especially if it’s a small HMO or within a council area with selective licensing.

If the property is unlicensed when a Section 21 notice is served, it’s invalid until the licence (or temporary exemption) is in place. Councils are increasingly using this as a defence to block evictions.

8. Serving Notice When There’s an Outstanding Council Action

If the local authority has served an Improvement Notice or taken Emergency Remedial Action, landlords cannot serve a valid Section 21 notice for six months after the notice is issued.

Some landlords overlook this entirely, particularly where they’ve rectified the issue quickly. But even if repairs are completed, the six-month bar still applies. Serving notice within that period is invalid, and you’ll have to wait until the restriction expires.

9. Poor Paperwork and Record Keeping

Every legal document relating to the tenancy — deposit certificate, EPC, gas certificate, “How to Rent” guide, licence, etc. — must be properly recorded and retained.Many landlords know they’ve served documents but have no proof. Courts and tribunals expect clear evidence that the tenant actually received the paperwork.

If you served documents by hand or email, keep a signed acknowledgement, proof of delivery, or contemporaneous email log. Without it, the judge may side with the tenant’s denial and invalidate your notice.

10. Failing to Carry Out a Pre-Service Compliance Audit

Before serving a Section 21 notice, the landlord must ensure that every legal precondition has been satisfied — even if the tenancy has been running smoothly for years.

Many landlords assume that because rent has been paid and there are no disputes, they can serve notice without issue. In reality, missing one of the above steps — even years ago — can unravel your case entirely.

A compliance audit checks every element: deposit protection, prescribed information, certificates, documentation, and timing. Professional eviction specialists (like us) run these checks routinely, catching issues before they reach court.

Final Thoughts

The Section 21 process is far from a formality — it’s a detailed legal procedure where even minor oversights can cost landlords thousands in delays and court fees.

Before serving any notice, it’s essential to:

• Review your entire tenancy file for compliance.
• Ensure all prescribed documents were served correctly.
• Confirm the property is licensed and up to date.

At Landlord Advice UK, we’re featured on Channel 5’s Nightmare Tenants, Slum Landlords, and we continue to achieve one of the highest success rates in landlord evictions nationwide. Our secret? Meticulous compliance checking, legal precision, and unrivalled experience.

Get in touch today for a free Section 21 compliance review, and avoid the costly mistakes that stop landlords in their tracks. Contact us here.