Assured Shorthold Tenancy Agreement UK: 7 Mistakes That Make It Unenforceable (2026)

An assured shorthold tenancy (AST) agreement is unenforceable when it omits prescribed information, fails to protect the deposit within 30 days, or uses terms that contradict the Housing Act 1988. Each of these errors can block a Section 8 possession claim, expose you to a penalty of one to three times the deposit, or make your rent increase notice legally worthless. Here are the seven most common drafting failures — and what to do instead.

Why the AST is stricter than most people assume

The assured shorthold tenancy is the default tenancy type in England and Wales under the Housing Act 1988 as amended by the Housing Act 1996. Landlords often treat the written agreement as a formality, assuming the tenancy is valid simply because the tenant moved in and paid rent. That assumption is wrong.

Courts have held that a tenancy can be legally periodic (and therefore harder to end) even where the written fixed-term document was never signed. The Renters' Rights Act, which received Royal Assent in 2025 and came into force in stages, further tightened the regime by abolishing fixed-term ASTs for new tenancies and replacing Section 21 no-fault eviction with a grounds-only possession framework. In 2026, any landlord whose agreement references Section 21 as an available remedy is already working from an outdated document.

Mistake 1: Not providing the How to Rent guide

Section 21A of the Housing Act 1988 (now effectively superseded by the Renters' Rights Act, but still relevant to tenancies started before the commencement date) required landlords to supply the government's "How to Rent" guide before relying on no-fault possession. Even under the new grounds-only regime, failing to provide the current version of the guide weakens your position considerably, since courts treat it as evidence of whether the tenancy was properly constituted.

The guide is updated regularly — use the version current at the date you issue the tenancy agreement, not the one from your template folder from two years ago.

Mistake 2: Deposit not protected within 30 days

Under section 213 of the Housing Act 2004, a landlord must protect any tenancy deposit in a government-approved scheme and serve prescribed information on the tenant within 30 days of receiving the deposit. The three approved schemes are the Deposit Protection Service, MyDeposits, and the Tenancy Deposit Scheme.

Miss that 30-day window and two things happen. First, a court can award the tenant one to three times the deposit amount as a penalty under section 214(4). Second, a Section 21 notice (for legacy tenancies) becomes invalid until the deposit is returned or properly protected. No other corrective step — protecting the deposit late, apologising in writing — cures the penalty liability retrospectively.

Mistake 3: Using a fixed-term for a new tenancy after the commencement date

The Renters' Rights Act 2025 converted all new ASTs into periodic tenancies from the moment the relevant provisions came into force. A written agreement that purports to create a two-year fixed term for a new tenancy entered into after that date is void as to that term. The tenancy becomes periodic from the outset.

This matters because rent increase notices under section 13 of the Housing Act 1988 have different validity requirements for periodic versus fixed-term tenancies. A notice served on the wrong footing can be challenged at the First-tier Tribunal, delaying or preventing the rent increase entirely.

Mistake 4: Rent review clause that bypasses the section 13 process

Many template agreements include clauses allowing the landlord to increase rent annually by giving 28 days' written notice, or tying increases to CPI without reference to statutory process. Under a statutory periodic tenancy, the only valid mechanism for increasing rent against a tenant's objection is a section 13 notice under the Housing Act 1988 — a formal document that gives the tenant one month's notice and the right to refer the proposed increase to the First-tier Tribunal (Property Chamber).

A contractual rent review clause does not override section 13 for periodic tenancies. If the tenant refuses to accept the increase and you have not served a valid section 13 notice, you are stuck at the old rent.

Mistake 5: Overclaiming tenant liability for repairs

The Landlord and Tenant Act 1985 section 11 imposes on landlords a non-excludable duty to repair the structure, exterior, and installations for water, gas, electricity, and sanitation. Any clause in the AST that purports to transfer these obligations to the tenant — "the tenant shall maintain the property in good repair", full repairing leases in residential contexts — is void. The clause cannot be enforced, and including it invites a disrepair claim.

The permitted scope of tenant repair obligations in a residential AST is limited to tenant-caused damage, internal decorative condition (where explicitly agreed), and garden maintenance. Anything beyond that range should be reviewed by a solicitor before the agreement is signed.

Mistake 6: No EPC, gas safety, or EICR documentation at the start of the tenancy

The Energy Performance of Buildings (England and Wales) Regulations 2012 require a valid EPC before marketing, and the Energy Efficiency (Private Rented Property) (England and Wales) Regulations 2015 require a minimum E rating (or a registered exemption) before a property can be let. The Gas Safety (Installation and Use) Regulations 1998 regulation 36 require annual gas safety checks with a copy of the certificate given to the tenant before they move in or within 28 days of the check. The Electrical Safety Standards in the Private Rented Sector (England) Regulations 2020 require an EICR from a qualified electrician before the tenancy starts, renewed at least every five years.

Failure to supply these documents does not automatically void the tenancy, but it does bar the landlord from serving a valid Section 21 notice for legacy tenancies and, under the Renters' Rights Act regime, may be raised as a defence to possession proceedings. A free England and Wales AST template should include a schedule listing every document that must be handed over at the outset.

Mistake 7: Prohibited fees written into the agreement

The Tenant Fees Act 2019 banned landlords and agents from requiring tenants to pay fees not permitted under the Act — things like administration charges, credit check fees, and end-of-tenancy professional cleaning requirements. Any such clause is unenforceable under section 2 of the Act, and a landlord who receives a prohibited payment commits a civil offence under section 12, attracting fines of up to £5,000 for a first offence and £30,000 for subsequent ones.

The permitted payments are: rent, a refundable holding deposit capped at one week's rent, a refundable tenancy deposit capped at five weeks' rent (or six if annual rent exceeds £50,000), payments for defaulting on rent or key replacement, and changes to the tenancy at the tenant's request capped at £50. Anything outside that list — even if the tenant signed the clause willingly — is void.

How to avoid all seven

Start with a current template rather than one you last updated in 2022. Check every rent review clause against section 13. Confirm the deposit is protected within 30 days, not 31. Attach an EPC, gas safety certificate, and EICR schedule. Remove any repair obligation that trenches on section 11 duties. Delete every fee clause that is not on the Tenant Fees Act 2019 permitted list. And if you are granting a new tenancy in 2026, remove every reference to Section 21.

The forms-legal.com AST template for England and Wales is updated to reflect the Renters' Rights Act 2025 and includes the mandatory prescribed information for deposit protection — it is a practical starting point before you get independent legal advice on any unusual terms.

What to do if your current agreement contains one of these errors

If the tenancy is already running, the correction depends on the error. A deposit that was never protected can be protected late, but the penalty liability remains — the landlord cannot escape a claim by remedying the defect after proceedings start. A void repair clause can simply be ignored by both parties, since it has no legal effect. A prohibited-fee clause cannot be cured by retrospective agreement; returning the money is the only safe route.

For new tenancies, there is no substitute for using an agreement that reflects the current law. The Renters' Rights Act changed the architecture of the residential tenancy significantly — the possession grounds under Schedule 2 to the Housing Act 1988 as amended, the removal of fixed terms, and the restriction on rent increases all interact in ways that older template documents do not handle correctly.

Courts apply the law as it stands at the date proceedings are brought, not the date the agreement was signed. A landlord who entered a tenancy in good faith using an outdated form still faces the statutory consequences of non-compliance.