Do I have to pay Ontario's Estate Administration Tax before I even receive the probate certificate?

Yes. Ontario's Estate Administration Tax is paid at the time you apply for a certificate of appointment of estate trustee, commonly called probate — it's a condition of the application being processed, not something billed afterward once the certificate is in hand. The estate trustee estimates the value of the estate's assets as of the date of death and pays the tax based on that estimate before the court will issue the certificate.

This can create a real timing problem: the estate trustee often needs to come up with the tax payment out of pocket, or from whatever estate funds are already accessible, before they have the legal authority the certificate provides to access the deceased's bank accounts or sell estate assets. Families sometimes underestimate this gap and are surprised that probate itself requires upfront funds rather than being paid once assets are liquidated.

Because the amount owed is based on an estimate that can later be corrected once true values are known, and because sourcing the funds to pay it before probate is granted is often the practical bottleneck in getting an estate moving, this is worth planning for early with the estate's lawyer rather than discovering it at the application stage.