What is a Notice of Objection to a will and how do I file one with the Ontario court?

A Notice of Objection is the document you file with the Ontario Superior Court of Justice to formally oppose a will being used to grant probate — known in Ontario as a Certificate of Appointment of Estate Trustee. You file it, under the Rules of Civil Procedure, in the court office handling (or expected to handle) the estate, naming the will in question and your ground for objecting: for example, lack of testamentary capacity, undue influence, improper execution, or the existence of a later will. Once the registrar records a Notice of Objection against an estate, no certificate of appointment can be issued based on that will while the objection remains outstanding.

You don't need to prove your case at the filing stage — only to identify a genuine concern and show you have a financial interest in the estate, such as being a beneficiary, an intestate heir, or a beneficiary under an earlier will. Filing is only the first step, though: it can lead to a court-ordered process requiring the will to be formally "proved," full disclosure, and potentially a trial. Because a Notice of Objection has real, immediate consequences for the estate and the people relying on that will, it's worth getting advice on your grounds and evidence before you file, not after.