Is mediation available or required for a passing of accounts dispute in Ontario?

Mediation is generally available for a passing of accounts dispute, and it's often a genuinely useful option, since these disputes are frequently as much about strained relationships and mistrust between beneficiaries and a trustee as they are about specific dollar figures. A neutral mediator can help the parties work through disputed entries and compensation questions without escalating everything to a full contested hearing.

Whether mediation is mandatory in a given case depends on the specifics of how the matter is proceeding through the court, but even where it isn't strictly required, parties can agree to try it voluntarily, and courts generally view genuine efforts to narrow or resolve disputes favourably. A mediated resolution can also be faster and less costly than a fully litigated hearing, which matters since legal costs in a contested passing can otherwise eat meaningfully into what beneficiaries ultimately receive.

That said, mediation works best when both sides are willing to engage honestly with the numbers rather than using it as a delay tactic, and it doesn't replace the need for a properly prepared, well-supported accounting in the first place. Anyone facing this kind of dispute should ask their lawyer whether mediation makes sense given the specific issues in play.