What you need to know
Gas Safety Certificates confirm that all gas appliances throughout a rental property have been inspected by a registered Gas Safe engineer, making them safe to use. They are meant to be renewed annually, and breaches of the regulations exposes landlords to a liability to large fines. With the Deregulation Act, from 1 October 2015 it became a prescribed requirement for Section 21 possession purposes for tenancy agreements commencing or renewed on or after that date that gas safety certificates must be provided in accordance with Regulation 36(6) of the Gas Safety (Installation and Use) Regulations 1998. The question is, how does this requirement affect tenancy agreements pre-dating 1 October 2015 but which are renewed on or after that date? Is the requirement for a gas safety certificate covering the period of initial occupation required for s21 purposes even though that initial occupation took place in, say, 2014, before this matter of compliance was made a prerequisite for s21 purposes?
What happened in Muca v El Amrani?
An AST was initially entered in 2014. The landlord did not have a valid gas safety certificate covering the time of initial occupation, though gas safety certificates were issued and provided annually from 2015 until 2024. The tenancy agreement was renewed for the first and only time in 2017. In January 2025 the landlord served a Section 21 notice seeking possession. The tenant claimed that the notice was invalid due to a gas safety certificate not being in place when the tenant first moved in in 2014. The s21 notice was held to be invalid. The landlord appealed and obtained a possession order. The tenant appealed to the Court of Appeal.
What happened in Harker v Hubert?
The tenant moved in in 2007. From 2007 onwards the landlord granted multiple renewal agreements annually. The landlord was unable to evidence that a gas safety certificate was provided covering the time of first occupation. In 2023, the other gas safety certificates were re-served and a s21 notice served. The tenant did not vacate, and the landlord brought a claim for possession and succeeded at first instance as the trial judge found that it was not a prescribed requirement to have given the initial-occupation gas safety record where the tenant went into occupation before 2015 (i.e. before the Deregulation Act came into force). The tenant appealed successfully. The Landlord appealed to the Court of Appeal.
Why is this important?
The tenants in both of these cases were the successful parties in the Court of Appeal. In Muca, the tenant’s appeal was allowed; in Harker, the landlord’s appeal was dismissed.
The law is thus clarified as follows: for tenancy agreements pre-dating 1 October 2015, but renewed on or after that date, compliance with Regulation 36(6) at the time of taking up occupation of the rental property (i.e. before 1 October 2015) is a prerequisite for serving a valid s21 notice. This has long been argued by tenant advisers, but it is only now that we have a clear understanding of the legal logic behind that position. On the face of it, it looks counterintuitive: how can a pre-requisite for a valid Section 21 notice be backdated? Why does a requirement that was only introduced for s21 notices on 1 October 2015 apply to move-in dates before then?
The Court of Appeal has clarified that there is no backdating at all. The Gas Safety (Installation and Use) Regulations have been in force for a long time. The Deregulation Act did not introduce a new requirement but only made it so that a s21 notice could only be relied on where those Regulations had been complied with at the time of first occupation by the tenant. All the Deregulation Act really says then, is that a landlord of tenancies to which that Act applies (i.e. starting on or renewed on or after 1 October 2015) must have done what he was already required to do in order to rely on a s21 notice. This is not backdating. That is the genius of Muca.
The argument sometimes used by landlord advisers, that so long as there is compliance with the Gas Safety (Installation and Use) Regulations at the start of the first tenancy renewal post Deregulation Act – always something of a weak argument, though sometimes successful – now has nowhere left to run.
Who does this impact?
Helpfully, the Court of Appeal Judgment was handed down on 30 April 2026, just one day before the Renters’ Rights Act 2025 came into force. The Renters’ Rights Act 2025 abolished Section 21 notices from 1 May 2026.
While the impact will therefore be limited to s21 cases already ongoing, the clarification will perhaps allow housing lawyers and housing judges sleep more easily at night.
What can we expect going forward?
Landlords can still issue s21 possession proceedings until 31 July 2026, if the notice was validly served before 1 May.
As always, the devil is in the detail with s21 claims, and entitlement to possession should be carefully checked before proceeding. At least the Muca decision gives clarity on one of the many potential risk points for s21 claims.
For further information on this topic, please contact the Real Estate Disputes team.
26 May 2026