7 Mistakes That Make a Section 21 Notice Invalid

Section 21 was abolished on 1 May 2026, but for tenants who received notices before that date — and whose landlords issued court proceedings before 31 July 2026 — the question of whether the notice was valid remains live. Even under the old rules, a significant proportion of Section 21 notices were invalid due to easily avoidable landlord mistakes. Here are the seven most common errors.

1. Deposit Not Protected (or Protected Late)

Under Section 215 of the Housing Act 2004, a landlord cannot serve a valid Section 21 notice if they are holding a deposit that has not been protected in an authorised scheme (DPS, TDS, or mydeposits). The deposit must be protected within 30 days of receipt, and the prescribed information (a formal document explaining the scheme and your rights) must be provided to the tenant within the same period.

Crucially, the bar is suspensory, not permanent. A landlord who failed to protect the deposit can remedy the situation by returning the deposit in full to the tenant before serving the Section 21 notice. However, an uncashed cheque does not count as return of the deposit — the money must actually be returned. If the deposit was not protected and not returned, any Section 21 notice served is invalid.

2. No Gas Safety Certificate Provided

Under the Gas Safety (Installation and Use) Regulations 1998 and Section 21A of the Housing Act 1988, a landlord cannot serve a valid Section 21 notice without having provided the tenant with a valid gas safety certificate. The certificate covers the gas appliances in the property and must be renewed annually.

Like the deposit protection bar, this is suspensory. A landlord who failed to provide the certificate before the tenancy started can give it to the tenant later — but must do so before serving the Section 21 notice. If the certificate was provided before the notice, the notice is not invalid on this ground (even if the certificate was provided late).

3. EPC Not Provided

The tenant must be provided with a copy of the property's Energy Performance Certificate (EPC) before the tenancy begins. Failure to do so bars the landlord from serving a valid Section 21 notice. Unlike some other bars, the EPC requirement cannot be cured by providing the certificate after the tenancy has started — if it was not provided before the tenancy commenced, the Section 21 bar is permanent for that tenancy.

This is one of the most significant bars because it applies even if the landlord later provides an EPC. Check whether you received an EPC before you moved in — if you did not, this alone may invalidate the Section 21 notice.

4. Wrong Form Used (Not Form 6A)

Section 21 notices must be served on the correct prescribed form — Form 6A. This form was prescribed by the Assured Shorthold Tenancy Notices and Prescribed Requirements (England) Regulations 2015. Using an older form, a non-prescribed format, or a form with errors can invalidate the notice.

Common errors include: using a pre-2015 form (no longer valid), leaving blank boxes unfilled, using the wrong version of Form 6A (the form is occasionally updated), or not completing the notice correctly. If you received a Section 21 notice, check whether it uses the current Form 6A and whether it has been completed correctly.

5. Notice Served During a "Retaliatory Eviction" Period

Under the Deregulation Act 2015, a Section 21 notice is invalid if it is served within 6 months of the landlord receiving a relevant complaint from the tenant or the local authority about the condition of the property. Specifically:

• If you complained in writing about the condition of the property, and the landlord served a Section 21 notice within 6 months of that complaint, the notice may be a retaliatory eviction.
• If the local authority served an improvement notice or emergency remediation notice on the landlord, a Section 21 served within 6 months is invalid.

This protection is designed to prevent landlords from using eviction as a weapon against tenants who raise repair complaints. Keep records of all repair requests and complaints.

6. HMO Without a Licence

If the property is a House in Multiple Occupation (HMO) and requires a licence under Part 2 of the Housing Act 2004 (mandatory HMO licensing for properties with 5 or more occupants in 2 or more households), the landlord cannot serve a valid Section 21 notice while the property is unlicensed. Many landlords do not know whether their property qualifies as an HMO or whether their local council operates additional licensing schemes.

Check whether your property might be an HMO (multiple tenants sharing facilities who are not all from one family) and whether your landlord holds the appropriate licence. Your local council can confirm whether a licence is required and whether one has been issued.

7. Notice Served Within First 4 Months of Tenancy

Under the Deregulation Act 2015, a Section 21 notice cannot be served during the first four months of the original tenancy (not the first four months of a renewal or periodic continuation). If the notice was served within four months of the start of the original tenancy, it is invalid regardless of the notice period stated.

This is a simple timing check but often overlooked. Count four months from the date your original tenancy agreement started. If the Section 21 notice was served before that date, it is invalid on its face.

The Practical Takeaway

For tenants who received Section 21 notices before the May 2026 abolition, checking validity on all seven grounds is essential before taking any action — including leaving the property. An invalid notice cannot be used to obtain a possession order from the court. Many landlords served technically defective notices and then relied on tenants not realising the notice was invalid. Use our free Section 21 checker or seek advice from Shelter or a housing solicitor before deciding what to do.