How this tool works
What the check tells you
The checker calculates a deadline from the dates and day periods you enter, then compares the served date with that deadline. “On or before” means the entered calendar date is no later than the calculated date; it does not establish the time of service or whether the notice reached the right person.
Under the construction payment framework, notices may need to state the sum considered due and the basis of calculation. The Act also provides for a payee notice in default of a payer notice in some circumstances. A date-only tool cannot assess notice content, service clauses, or the effect of a previous notice.
What to verify
Check the signed terms for who may serve the notice, the permitted delivery method, defined days, and any required form. Keep a copy and proof of service.
Assumptions and limitations
This is a browser-based estimate using the figures and periods you enter. It does not verify a contract, decide legal validity, calculate tax liability or replace current HMRC guidance. Reviewed 7 October 2026.
Frequently asked questions
Does “on time” mean the notice is valid?
No. This compares dates only. It cannot assess service method, recipient, content or authority.
Which period should I enter?
Use the relevant period in the signed contract, including any definition of working days or service rules.