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15 minute read Published on Jan 10, 2026 by BrokerLink Communications
Getting into a car accident is stressful enough without having to figure out who is at fault. In Ontario, the process of determining fault is streamlined through standardized Fault Determination Rules, which all insurance companies in the province use to assign responsibility following a collision. These rules do not look at police reports, weather conditions, or personal opinions. Instead, Ontario fault determination rules follow strict collision scenarios under Regulation 668 of Ontario’s Insurance Act.
The goal of these determination rules is to ensure fault is assigned fairly and consistently to streamline the entire process. Whether it's a minor fender-bender or a multi-vehicle accident, insurance companies apply these rules to determine a percentage of fault for all parties involved, from 0% (no fault) to 100% (entirely at fault).
So, why does this matter? Fault determination affects your claims payout, your deductibles, and future insurance rates. For example, even if no one is injured in a collision, being assigned 50% fault can result in higher car insurance costs the next time you're up for a renewal. With premiums increasing by 8.8% from 2023 to 2024, and even more into 2025, knowing how fault is assigned is more important than ever.
Otherwise, you could unknowingly accept liability for a car accident or miss the opportunity to challenge an assessment. In this guide, we're breaking down all the information you need to know about Ontario's Fault Determination Rules, from Section 668 of the Insurance Act, to common misconceptions, how to dispute decisions, and more.
Ontario’s Fault Determination Rules are legally outlined in Section 668 of the Insurance Act and expanded upon further in Regulation 668, which is also known as Automobile Insurance - Fault Determination Rules. This act essentially provides the province with the legal authority to implement a standardized framework for assessing fault in motor vehicle accidents. This regulation applies to all 9.4 million vehicles with car insurance policies in Ontario. What makes Section 668 unique is that car insurance companies are expected to match the details of the accident they're handling with one of the many predefined accident scenarios listed within the section. It also comes with illustrated diagrams and outlines rear-end collisions, left-turn crashes, lane merges, and more!
Another aspect that stands out about Section 699 of the Ontario Act is that the law emphasizes that fault determination is strictly independent of traffic or criminal convictions. What this means is that a driver may not be found guilty of a traffic offence in court, but can still be considered 100% at fault for a collision under these rules. At the same time, the laws do not take into account external factors such as weather conditions or mechanical failures, as they assume all drivers are expected to maintain full control over their vehicles and follow traffic rules.
Those reviewing Section 668 will also notice that a key element of the regulation is shared fault. This enables fault to be shared between multiple parties involved in car accidents, whether it be 50/50, 70/30, 60/40, etc., depending on the facts surrounding the collision and how applicable rules apply. Ultimately, this shared fault ensures that all parties' actions are fairly considered. For a full look at Regulation 668, you can visit the Ontario government’s official law site.
When there are two or more vehicles involved in a car accident in Ontario, insurance companies aren't left to make guesses on who's to blame or solely rely on police reports. Using structured, standardized diagrams of various accident scenarios, they're able to streamline the claims process and maintain consistency across the process as a whole. In other words, rather than relying on subjective judgments, they reflect how vehicles interacted on the road and what each driver was doing at the moment of impact. Based on this information, insurance providers then assign each driver a percentage of fault. Below is an overview of the factors considered when determining fault:
Once a claim is filed by a policyholder, an insurance adjuster assigned to their file will collect the following information:
Witness statements (if applicable)
Photos, dash cam footage, and traffic camera footage
Police reports (if applicable)
Diagrams or hand-drawn illustrations
Statements from all drivers involved in the collision
Other evidence provided to them
With this information, they will compare the details of the accident to the scenarios outlined in Ontario's Fault Determination Rules. Again, each of the rules includes a visual and written description. The one that most closely matches the situation outlined in the rules will be used when determining fault.
So, what happens if a car accident scenario doesn't exactly fit into the standardized ones within Ontario's Fault Determination Rules? This is where Section 5, also known as the default mechanism, kicks into gear. This section states, "If an incident is not described in any of the rules, the degree of fault of each insured person shall be determined in accordance with the ordinary rules of law.”
For example, let's say that two vehicles collide in a roundabout, and no diagram directly applies to the scenario. If it's unclear who had the right-of-way or if both motorists acted unsafely, the insurance company may choose to assign fault 50/50, unless other evidence shows that one motorist was clearly responsible. They may also choose to use fault determination rules that are closest to what happened.
While all car accidents are different, some are more common than others in Ontario. Let's take a closer look at some common accidents and how fault determination is found below:
According to a 2020 Ontario Road Safety Report, the province saw 31,914 rear-end collisions. Below, we explain sample situations, fault decisions, and the logic behind them:
Scenario: Driver A rear-ends Driver B, who has stopped at the traffic light.
Who’s at fault: Typically, Driver A would be 100% at fault for the car accident.
Why: Following cars are required by law to keep a safe distance between themselves and the cars in front of them. This way, if the driver in front of them quickly brakes, the following cars will still be able to stop safely.
Left-turn accidents at an intersection are one of the most common types of car accidents across Ontario and the rest of Canada. Here are illustrative scenarios with fault breakdowns and why they were decided:
Scenario: Driver A turns left while Driver B travels straight through the intersection in the opposite direction, causing a collision.
Who’s at fault: Driver A, who is making the left turn, is found at fault 100% of the time.
Why: If there are no signs saying otherwise, the driver who is turning must yield to the driver travelling in a straight line.
Examples of scenarios and fault attribution—with explanations—follow when changing lanes:
Scenario: Driver A sideswipes Driver B when changing lanes.
Who's at fault: Driver A is 100% at fault under Rule 10 of Ontario's fault determination rules.
Why: Drivers in their respective lanes have the right of way. They are not required to brake, swerve, or predict a lane change from you.
A survey by Canadian Underwriter finds that 59% of surveyed Ontario motorists had encountered some form of parking lot collision. Here are sample scenarios, fault decisions, and the rationale behind them:
Scenario: Two vehicles are backing out of their parking spaces and collide with one another.
Who’s at fault: Both vehicles are found 50% at fault under Rule 24(5) of Ontario's fault determination rules.
Why: Both drivers are liable for inspecting the area around them. Therefore, each has an equal responsibility to ensure that their path is clear before backing up.
When there's more than one or more automobiles involved in a collision, determining who is at fault can become trickier. And in some situations, both drivers contributed to the outcome of the collision. In this case, the fault determination rules allow split-fault percentages such as:
50/50 when both drivers violated a rule or acted carelessly.
75/25 if one driver created the situation, but the other failed to respond appropriately.
For example, if a driver changes lanes without signalling their intent (which makes them primarily at fault), but the other driver is speeding excessively in their lane, it's possible that insurance companies split fault 75/25 rather than assigning it entirely to the car changing lanes. Remember, these percentages matter because they directly impact how claims are paid and whether a driver's premiums increase the following year.
Many Ontario drivers can become frustrated by how fault is determined after a collision, and it's partly due to misconceptions surrounding Ontario's fault determination rules. Below, we've outlined some of the most common misconceptions, so you can have a better idea about how these rules apply. Common myths about car accident fault include:
This is false. Insurance companies follow Fault Determination Rules, not the Highway Traffic Act or the Criminal Code. That means while you may be able to avoid a ticket or fines, you can still be considered completely at fault for insurance reasons. Charges refer to criminal activity; fault refers to driving actions and responsibilities at the time the collision occurred.
Wrong. Fault is not impacted by bad weather, reduced visibility, or icy roadways. The regulations maintain that all drivers should adapt their driving to their driving conditions. If you struck another automobile due to fog, black ice, or sunlight, the regulations will hold you liable if your driving contributed to the accident.
Again, this is not true. Being struck by another vehicle does not necessarily imply that you are not at fault in the matter. Even if the other driver hit you, you could be entirely or partly to blame if you cut off another driver, ran through a red light, or reversed out of a parking space without looking.
This is also not true. While someone may admit fault at the accident scene, insurance companies will still rely on diagrams, witness statements, and the Fault Determination Rules, not what is said. Even if the other driver claims "it was my fault," the insurance adjuster will assess the situation before fault is determined.
Being at fault for a collision can have a direct impact on your claims payout and insurance premiums moving forward. That’s why understanding how fault influences your insurance claim is so important. Let's take a closer look at the impact fault can have in more detail below:
Ontario operates under a no-fault insurance system. This means that your own insurance company provides direct compensation for property damage and injuries, rather than the other insured driver's company, regardless of how fault is determined. That being said, this doesn't mean that fault determination doesn't matter. For example, your insurance provider will cover the following:
Damage to your vehicle (if you have collision car coverage or all-perils coverage).
Medical expenses and rehabilitation (under accident benefits coverage).
Damage to other people's property (under third-party liability car insurance).
Rental car, other transportation costs, or towing after an accident(if you've added this optional policy to your plan).
However, whether or not your insurance company recovers costs from the other driver’s insurer or pays for the loss itself depends on the fault determination of your accident. For example, if you are found to be 0% at fault, your insurance company can recover payout costs from the other driver. But if you are partially at fault, they may not be able to recover their losses.
Being found 25% at fault or more typically results in the following when you're up for a car insurance renewal:
A premium increase of anywhere from 25% to 50% for up to six years.
The accident will be recorded on your insurance history, which will follow you, even if you decide to switch insurance providers.
One thing to note is that if you have opted to add accident forgiveness to your insurance plan, your first at-fault accident will not increase your premiums. This is an optional endorsement designed to reward safe driving behaviours in Ontario. Therefore, if you're a new driver or you've never been assigned fault in a collision before, adding this to your plan can help you avoid an increase in your rates. Note, this is a one-time endorsement. Need auto insurance? BrokerLink has you covered. Connect with a broker and get your quote today.
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If you do not agree with your fault determination following a collision, there are formal and informal steps you can take to dispute it, especially if you believe your insurance company misunderstood the facts of the collision or that the wrong fault determination rules have been applied to your claim. Steps for assessing fault in a car crash:
The first thing you need to do is request a written explanation of how fault was assigned in your claim. This should include:
The specific fault determination rule(s) from Regulation 668.
A summary of the evidence that was used.
Ultimately, before moving forward with your dispute, you must have a better understanding of why your adjuster made their decision in the first place.
From then on, if you still believe their fault determination was incorrect, you'll need to go ahead and gather any additional evidence that can support your version of events. This may include:
Dashcam footage.
Witness statements.
Traffic camera images and video.
Relevant traffic signs.
Diagrams showing the actual positions of the vehicles.
Once you have this additional evidence, pay close attention to any inconsistencies between your evidence and what the insurer used to apply the rule. Even the smallest of details can be enough to change how the fault determination rules are applied in your claims process.
Next, you'll want to go ahead and request a follow-up meeting with your adjuster. Respectfully present your new evidence and explain how you interpret the fault determination rule. In the event your adjuster still agrees with their original decision, you can ask to speak with a manager or claims supervisor. Remember to remain factual and professional. You should also keep a copy of all communication you have with your insurance company.
Now, if, after you've spoken with a claims supervisor, you are still not sure how they assigned fault, you can ask about your insurance company's internal dispute process. Most insurance companies in Ontario have a formal complaints process you can follow.
In the event your fault determination rule dispute goes unresolved, you can go ahead and contact the General Insurance Ombudsman Service. This is a fee, neutral third-party organization that helps Canadians resolve complaints with their insurance companies. You can find more information on how to file your complaint on their website.
If the outcome of the fault determination significantly impacts your premiums or legal liability in any way, you may want to speak with a lawyer. They can help you assess whether you have any legal grounds to pursue legal action or file a complaint with Ontario’s Financial Services Regulatory Authority (FSRA). One thing to remember is that disputes can take time. However, if you are confident that the decision was incorrect, it may be worth pursuing.
One of the most confusing parts about getting into a car accident in Ontario is the difference between legal fault and insurance fault. While these terms sound familiar and may be used interchangeably by accident, they do serve different purposes and follow different rules. Let's take a closer look at these differences below:
Legal fault refers to liability in the court of law, whether civil (lawsuits) or criminal (charges). In court, a judge or jury of peers will decide legal fault based on evidence, testimony, and more. For example, let's say a driver runs a red light and causes an accident. In court, the driver may be charged with a traffic offence or sued for damages by the other motorist involved. In this case, the judge could find them 100% legally liable. On the other hand, if they are not charged or convicted of a traffic or criminal offence, the driver's insurance company can still determine they are at fault for what happened.
Ontario’s Fault Determination Rules determine insurance fault. These rules use predetermined scenarios (e.g., rear-end collision, left turn across traffic) to assign fault percentages to all drivers involved. These decisions help insurers process claims more efficiently and consistently across policyholders, regardless of whether any legal charges have been laid against any of the drivers. For example, if two drivers back out of their parking space and collide, both are assigned fault at 50%, even if one of the drivers insists they have the right-of-way. Neither driver breaks the law, and no one is charged.
To further demonstrate how fault determination rules apply in Ontario, take a closer look at these two hypothetical scenarios below:
Jason is driving on Highway 401 when traffic suddenly slows down. He brakes in time, but the car behind him doesn't stop quickly enough. As a result, the driver (Michelle) causes a rear-end collision. Michelle claims that she didn't have enough time to react to Jason hitting his brakes. Under Rule 6 of the Fault Determination Rules, drivers who rear-end another vehicle are 100% at fault, no matter what the road conditions are like.
Nicole is driving in the middle lane of the Gardiner Expressway during rush hour. She signals and begins moving into the left lane. At the same time, Daniel, who is already driving in the lane, can't brake in time. Daniel hits the back side of Nicole's vehicle. According to Ontario’s rules, the driver who changes lanes is usually 100% at fault if there’s a collision.
Whether it's a minor fender bender or a more serious collision, if you're involved in a collision in Ontario, the minutes and hours after what happened can play a major role in how your insurance claim is handled. Here's what you need to do to protect yourself after an accident and ensure fair fault determination rules are applied to your case:
The first thing you need to do is stay calm and check yourself and your passengers for injuries. If you are injured, contact emergency services right away. If no injuries are reported, you'll then need to move your vehicle to a safe location if possible. This will prevent traffic congestion and lower the risk of another accident occurring.
Take as many photos and videos of the accident scene as possible, including:
The overall scene from different perspectives.
Vehicle damage.
Road conditions, skid marks, or traffic signs.
Licence plates.
Get the other driver’s:
Name and contact info.
Insurance company and policy number.
Driver’s licence number.
Vehicle make, model, and licence plate.
If there are witnesses, ask for their names and contact details as well.
Remember, don't admit fault at the scene, even if you caused the accident.
You are legally obligated to contact law enforcement if:
The collision involves damage to private, municipal or highway property.
Someone is injured.
The damage to vehicles is over $5,000.
If the collision involved pedestrians or cyclists.
The other driver has left the scene of the accident.
The other driver is uninsured or underinsured.
You believe criminal activity is involved.
The collision involves a commercial vehicle.
Once you are home, we recommend contacting your insurer as soon as possible to report the accident and start your claims process.
Ontario's fault determination rules are there to make insurance claims more fair and predictable, which is why all drivers in the province should understand how they work. By being informed, you can handle the aftermath of a collision more calmly, gather the right evidence, and know what to expect when filing your claim.
Remember, if you don't agree with how fault is assigned, there are options you can take to dispute your claim. Whether you have questions about fault determination rules in general, are unsure how fault is assigned in a multi-vehicle crash, or have other questions about your insurance, the experienced brokers from BrokerLink are here to help. To work with us, contact us over the phone or by email. You can also get a free car insurance quote using our online quote tool at your convenience!
