What is a certificate of substantial performance and why does it matter for a lien in Ontario?

A certificate of substantial performance is a formal document, issued under the Construction Act once a contract is substantially - though not necessarily completely - finished, confirming that the work is ready for use or is being used for its intended purpose, with only minor items remaining. It's typically issued by the contract's payment certifier (often an architect or engineer on larger projects) or, on smaller projects, agreed between the parties, and it must be published in the way the Act requires, generally by posting notice at the site and publishing in a construction trade newspaper.

Publishing the certificate matters enormously because it starts the clock on key lien deadlines - contractors and subcontractors involved in the work up to that point generally must preserve any lien within 60 days of the certificate's publication, rather than waiting for full deficiency-free completion of the entire contract. It also affects when holdback tied to the substantially performed work can potentially be released. Because publication date, not the actual state of the work, is what triggers these deadlines, confirming exactly when and how a certificate was published is often the first thing to check in any lien timing dispute.