What is the Section 20B 18-month rule?
Section 20B of the Landlord and Tenant Act 1985 says a service charge cost incurred more than 18 months before the demand for it is served cannot be recovered — unless, within that 18 months, the leaseholder was notified in writing that the cost had been incurred and would later be charged. It is a common winning ground at tribunal.
Section 20B exists to stop landlords sitting on old bills and then demanding payment years later, when the leaseholder has no realistic way to check or challenge them. It sets a strict time limit between the moment a cost is incurred and the moment a valid service charge demand for it is served.
The 18-month time limit
The general rule in Section 20B(1): if a cost was incurred more than 18 months before the demand is served, the leaseholder is not liable to pay it. The clock runs from when the landlord became liable for the cost (usually when it received the invoice or made payment) to when it serves the demand on you.
Why it wins at tribunal
Section 20B is one of the most effective grounds a leaseholder can raise, because it is a hard-edged time test rather than a matter of judgement. If the landlord cannot show that either the demand or a qualifying written notification landed within 18 months of the cost being incurred, the charge simply falls away — however reasonable the underlying spend might have been. Delayed major works billing and late balancing charges are frequent casualties.
How to use it
To check a charge against Section 20B, line up three dates: when the cost was incurred, the date of any written Section 20B(2) notification, and the date the demand was served on you. If more than 18 months separates the cost from the demand, and there was no qualifying written notification in between, the cost is arguable. Because the burden is on the landlord to prove the timeline, refusing to produce dated invoices is itself telling.
Section 20B goes hand in hand with the general test that charges must be reasonable under Section 19 of the Landlord and Tenant Act 1985 — but it is a separate, and often quicker, route to knocking out a demand.
How this shows up in your service charges
Late-arriving bills for works done a year or two ago are exactly where Section 20B bites. Our free AI audit reads your demands and accounts, lines up the dates, and flags any costs that may be time-barred under the 18-month rule — so you can raise it before you pay. Want the full process? See our guide to challenging service charges.
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