How do I get official proof from the municipality that my property has legal non-conforming use status?

There generally isn't a single automatic certificate a municipality issues confirming legal non-conforming use status just because a property qualifies; rather, proving the status usually means assembling evidence, such as historical records, past permits, tax assessment history, aerial photographs, or affidavits from long-term neighbours or previous owners, that together show the use was lawfully established before the relevant zoning change and has continued without a significant interruption since.

Some municipalities will provide a written opinion or confirmation letter based on evidence an owner submits, though this is generally a municipal assessment of the evidence presented rather than a formal, binding certification that can never be challenged later, and the strength of that opinion depends heavily on how solid the underlying documentation actually is. Because these disputes often surface years later, when memories have faded and records are harder to find, owners who believe their property benefits from legal non-conforming use status should proactively gather and preserve supporting documentation now, well before a sale, a permit application, or an enforcement issue forces the question, rather than waiting until the status is actively challenged.