How can I find out if a probate application has been filed for someone in Ontario?

There is no single answer here, because whether you can find out depends on what has been filed and where. A probate application is filed at the Superior Court of Justice in the county or district where the deceased lived at the time of death. If the deceased lived outside Ontario, it is filed where they owned Ontario property.

Keep in mind that probate is not always required. An estate normally must be probated if the deceased owned real property, or assets held by a financial institution, in their own name. So a missing application does not always mean something is wrong. Applications are usually processed within 15 business days, so a recent filing may not have produced a certificate yet. The document the court issues is called a Certificate of Appointment of Estate Trustee.

Before filing, the applicant must send the signed application to the estate beneficiaries. If you are a beneficiary, you may therefore receive it directly. How a search for a will works depends on the facts, so a lawyer can confirm the right route.