Section 20B and the 18-Month Rule Explained

What the rule says

Section 20B of the Landlord and Tenant Act 1985 places a general limit on how late a landlord can first demand a service charge cost after incurring it - generally 18 months, running from the date the landlord incurred the relevant cost. That date may not be identical to the date the works were completed, the invoice date, or the date the contractor was paid; determining when a cost was incurred can depend on the contractual and factual circumstances. The idea is that leaseholders shouldn’t face a large, unexpected bill for costs that happened so long ago they had no reasonable chance to budget or query them at the time.

The notice exception

The rule isn’t absolute. The 18-month restriction won’t apply in the same way if, within that period, the landlord gives the leaseholder written notice that the relevant costs have been incurred and that the leaseholder will subsequently be required under the lease to contribute to them through a service charge. Whether a specific piece of correspondence actually counts as this kind of notice is a detailed, fact-specific question - not something a general guide (or an automated tool) can determine for your particular documents.

Why this is a chronology question, not a conclusion

It’s important to be precise here: this rule doesn’t mean a demand is automatically “too late” just because it feels like it arrived a while after the works. Whether a demand actually falls foul of the 18-month rule is a question only a tribunal can ultimately decide, based on the exact dates involved and whether any notice exception applies. What’s genuinely useful at this stage is building an accurate chronology - not concluding anything from it yourself.

Building your own chronology

• The contract and any invoices, completion certificates, or accounting records that might show when the relevant cost was actually incurred
• The date the works were carried out or completed, and the invoice date - useful evidence, but not necessarily the same as the date the cost was incurred
• The date of any notice referencing the cost, if one was sent before the formal demand
• The date the formal demand for payment actually arrived

These dates help establish when the relevant cost may have been incurred and whether the statutory time limit may be engaged - collecting them accurately is exactly the kind of dated sequence a Defence Pack builds automatically from your own documents, alongside the rest of your evidence check.

If the gap looks significant

The right next step is to raise it as a clear, factual question with your landlord or managing agent - asking for the dates and any notice they say extends the period - rather than assuming the charge is unenforceable and simply not paying it. See our guide to writing an effective observation letter and, if you want to understand the further routes available, which escalation route handles what.