Step 1: Get the rule number
Ontario fault is assigned by matching your crash to a scenario in the Fault Determination Rules (Regulation 668). Ask your adjuster one precise question: "Which rule number did you apply?" They must tell you. Look the scenario up — the dispute is almost never about the percentage; it's about whether the right scenario was chosen.
Step 2: Attack the scenario with evidence
- Dashcam footage — the single most decisive evidence there is. Yours, the other driver's, or a witness's.
- Independent witnesses — someone not in either car. Get written statements with contact details.
- Photos of positions and damage — impact points often prove which version of events is physically possible.
- The police or CRC report — not binding on fault, but inconsistencies in the other driver's story matter.
Send it in writing, name the rule you believe applies instead, and ask for a written response.
Step 3: Escalate — the free ladder
Adjuster won't budge? Every insurer must have a complaint officer / ombudsman — ask for the complaint process in writing and file. Still stuck? The General Insurance OmbudService (GIO) reviews disputes with insurers free of charge. For the dollars at stake in a fault flip — years of surcharge — this ladder is worth climbing.