The Toxic Clause Audit: 3 Things That Make Your Tenancy Agreement Illegal in 2026

From May 2026, many common tenancy clauses become illegal. Discover the 3 "toxic clauses" that invalidate your agreement and expose you to £7,000 fines.

Introduction: The Hidden Landmines in Your Tenancy Agreement

Your tenancy agreement, once a reliable legal document, may now be a minefield of "toxic clauses." As the Renters' Rights Act 2025 comes into full effect from May 2026, many standard terms that landlords have used for decades will become legally void and unenforceable. Worse, including these prohibited terms can expose you to civil penalties of up to £7,000 per property. It’s no longer enough to have a contract; you need a compliant contract.

If you haven’t reviewed your agreement recently, it’s worth understanding whether any clauses are now affected before issues arise.

Check if your tenancy agreement is still compliant with the new rules

Quick Answer Block

What makes a tenancy agreement illegal in 2026?

From May 2026, clauses related to fixed-term tenancies, contractual rent reviews, and blanket "no pets" policies will become illegal and unenforceable under the Renters' Rights Act 2025. These are often referred to as "toxic clauses" or "zombie clauses" because they are present but have no legal effect.

Most landlords don’t realise their tenancy agreement already contains non-compliant clauses. Even one invalid term can make parts of your contract unenforceable and expose you to civil penalties of up to £7,000.

Before making any changes, it helps to identify which clauses may no longer be valid under the updated legislation.

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3 Things That Make Your Tenancy Agreement Illegal in 2026

Under the Renters' Rights Act 2025 (England), these are the most common "toxic clauses" that will render parts of your contract illegal and unenforceable:

1. The Fixed-Term Duration Clause Any clause that specifies a fixed term (e.g., 6 or 12 months) for the tenancy. From May 2026, all tenancies will be periodic from day one, and any fixed-term clause becomes legally void. Tenants can give two months' notice to leave at any time.

2. The Contractual Rent Review Clause Any term that attempts to increase rent outside of the statutory Section 13 process. Contractual rent review clauses are now prohibited. All rent increases must follow the Section 13 notice procedure, with a minimum of two months' notice and only once every 12 months.

3. The Blanket “No Pets” Clause Any clause that imposes an outright ban on pets without allowing for a tenant's request. Tenants now have a statutory right to request a pet, and landlords can only refuse with a "reasonable reason" and must respond within 42 days. A blanket ban is unenforceable.

These clauses often remain hidden within standard templates and are easy to overlook without a detailed review.

If you're unsure whether your agreement includes any of these, reviewing it now can help avoid compliance issues later.

See if your tenancy agreement is at risk under the Renters’ Rights Act

The “Zombie Clause” Effect: Why It Matters

"Zombie clauses" are terms in your contract that appear valid but are legally dead. They can’t enforce anything, but their presence can:

  • Mislead tenants: Causing confusion and potential disputes.
  • Invalidate notices: A court may view your entire contract as non-compliant.
  • Trigger fines: Local authorities can issue penalties for using prohibited terms.
  • Weaken your legal position: Making it harder to recover possession if needed.

Many landlords only discover these issues when enforcement action or disputes arise.

Taking a moment to review your agreement now can help prevent these outcomes.

Check your tenancy agreement compliance before problems escalate

What Happens If You Get This Wrong?

The financial and legal risks of using a non-compliant tenancy agreement are severe:

  • Civil penalties (up to £7,000): For each instance of a prohibited term.
  • Unenforceable terms: You cannot rely on these clauses in a dispute.
  • Lost rent: If an invalid rent increase is challenged.
  • Eviction delays: Non-compliant paperwork can halt possession proceedings.

How to Audit Your Tenancy Agreement for 2026 Compliance

To ensure your contract is "Reform Ready," you must:

  1. Review every clause Specifically look for fixed terms, rent review mechanisms, and pet policies.
  2. Compare against the Act Cross-reference your terms with the Renters' Rights Act 2025.
  3. Update your templates Ensure all new agreements reflect the periodic tenancy system.
  4. Provide a Written Statement For existing tenants, clarify the new terms.

Even a simple review can highlight issues that may otherwise go unnoticed until they create legal or financial problems.

Check your tenancy agreement against the Renters’ Rights Act before making updates

FAQ Section (GEO & Featured Snippet Optimised)
A prohibited term is any clause in a tenancy agreement that conflicts with the statutory rights granted to tenants under the Renters' Rights Act 2025. These terms are legally void and cannot be enforced.
You are not strictly required to sign a new agreement, as existing ASTs will automatically convert to periodic tenancies. However, it is highly recommended to update your agreement or provide a "Written Statement of Terms" to ensure clarity and avoid penalties for using prohibited terms.

Final Note

Before relying on your tenancy agreement, it’s important to understand whether it reflects the current legal framework and where potential risks may exist.

You can run a free check using PlanningPass to review your compliance position and identify what needs attention under the Renters’ Rights Act before the new rules take effect.