I bought an Ontario property and now someone else is claiming they own part of it — what do I do?

Discovering a competing ownership claim after you close on a property is a serious matter, but Ontario's land registration system and title insurance provide important protections.

If the property is under the Land Titles system (most Ontario properties are), your registered title is generally guaranteed by the province under the Land Titles Act. A registered owner in good faith who paid value is entitled to rely on the register, and a third party claiming a competing interest will face a high threshold to displace a registered title. The Land Titles Assurance Fund can compensate innocent purchasers in certain situations where the register turns out to be inaccurate.

If you purchased title insurance — which is standard practice in Ontario — your policy should cover title defects that existed at closing, including certain adverse claims, undisclosed liens, and encumbrances. Review your title insurance policy and notify your insurer promptly if a claim arises. The insurer will defend your title and, if a loss results, indemnify you up to the policy limit.

Regardless of title insurance, you should also contact a real estate litigation lawyer immediately. Competing ownership claims can escalate quickly, and early legal advice preserves your options. Your lawyer can assess the claim's legal basis, advise on whether a court application is needed, and communicate with the claimant on your behalf.