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18-month rule checker: was your service charge billed too late?

Enter when the cost was incurred and when you were first billed, or warned in writing. The checker shows whether the 18-month limit in section 20B appears to be breached. It runs in your browser; nothing is sent anywhere.

England and Wales · Law checked 24 October 2026 · Not legal advice

This calculator gives general pointers, not legal advice. It can't see your lease or your landlord's documents. Free advice: LEASE.

How the 18-month rule works

Section 20B(1) of the Landlord and Tenant Act 1985 says you are not liable to pay the part of a service charge that reflects costs incurred more than 18 months before the demand was served on you.

The exception is section 20B(2): the rule doesn't apply if, within the 18 months beginning with the date the cost was incurred, you were notified in writing that the cost had been incurred and that you would later have to contribute through the service charge. LEASE says the notice should give a figure for the actual costs, but it doesn't need to tell you your exact share.

What the checker does

Finds the 18-month line: the same day of the month, 18 calendar months after the cost was incurred. If that month is shorter (for example, 31 August to February), it uses the last day of the month, including 29 February in leap years.
Demand before the line: in time. Demand on the line: probably in time, because the cost wasn't incurred more than 18 months earlier, but it is flagged as borderline. Demand after the line: the rule appears to apply, unless a notice was given in time.
Notice: must be given within the 18 months beginning with the date the cost was incurred, so a notice on the line date itself is flagged as possibly one day late.

Caveats

"Incurred" generally means when the landlord was invoiced or paid, not when the work was done (Burr v OM Property Management [2013] EWCA Civ 479). Check each invoice: one bill can contain costs with different dates.
On-account demands: if your budget payments already covered the cost, the rule usually doesn't bite. It matters most for balancing charges and one-off bills.
Served, not dated: what counts is when the demand was served on you. Keep envelopes and emails.
Reserve funds are treated differently: see reserve funds.

In Wales

Section 20B applies in the same way in England and Wales. In Wales, disputes go to the Leasehold Valuation Tribunal.

Changes on the way (not yet law)

Section 54 of the Leasehold and Freehold Reform Act 2024 will replace the section 20B(2) notice with a "future demand notice" in a form set by regulations. The regulations may also limit what can be recovered to an estimate given in the notice, or bar costs demanded after an expected date. This was not in force when we checked in October 2026, and no regulations have been made. Until then, the current rule above applies. See the 2024 Act timetable.

Questions

What if the demand came exactly 18 months after the cost?

Section 20B applies to costs incurred more than 18 months before the demand, so a demand on the same date 18 months later is probably in time. It's on the line, so check the exact date of service and get advice before relying on it.

When is a cost 'incurred'?

Generally when the landlord is invoiced or pays, not when the work is carried out (Burr v OM Property Management [2013] EWCA Civ 479). Ask to see the invoices under section 22.

What makes a valid section 20B(2) notice?

It must be in writing, given within 18 months of the cost being incurred, say the costs have been incurred (with a figure) and say you'll have to contribute through the service charge. A vague warning that costs may rise is unlikely to be enough (Brent LBC v Shulem B Association [2011] EWHC 1663 (Ch)).

Does the 18-month rule apply to estimated or on-account charges?

Usually not, where the on-account payments already covered the cost. It can apply to a later balancing charge demanded more than 18 months after the cost was incurred.

Does the 18-month rule apply in Wales?

Yes. Section 20B extends to England and Wales.

Is the 18-month rule changing?

The Leasehold and Freehold Reform Act 2024 will replace the 20B(2) notice with a prescribed 'future demand notice', but that section was not in force as of October 2026. The current rule still applies.