Insurance companies decide who’s at fault in an accident to determine whether to pay claims and to assess risks going forward. When it’s not clear who’s to blame, an insurer generally conducts an investigation to assess liability. The result not only determines whether you get reimbursed for damages, it also can affect your policy rates.

Finding Fault

Laws dictate who can file a claim and other process issues, but there aren’t laws about who’s at fault in which accident scenarios. Fault for an accident is usually determined solely by insurance companies. In occasions when the police cite one driver as being responsible for an accident, the insurers aren’t necessarily bound by that determination and can conduct their own investigation. They often do.

Sharing the Blame

Typically, an auto insurer ends its investigation by finding one or both drivers at fault. If it can’t decide it can distribute the fault proportionately. In a three-car accident, for example, an insurance company might assign one driver 60 percent of the fault and the other 40 percent. If you’re the third driver and not to blame at all, you’d be able to file a claim with both drivers’ insurance companies and they would determine who paid for what. This can be especially critical in states where being assigned any blame makes you ineligible to recover money from another provider for damages.

Hit and Run

If your car is damaged by an unknown party -- like if your car gets sideswiped by a hit-and-run driver -- your insurance company will probably want you to file a report with the police. Find out whether anyone witnessed the incident or left a note, when practical. If the police and your insurer can’t find the guilty party, you’ll have to turn to your insurer to pay for the damages, which are subject to the deductibles and rules of your policy.

Rising Premiums

If your car is damaged and the culprit can't be found, you may wind up paying for it anyway. Such accidents affect your premiums, but perhaps not in a good way. If this is your first claim your rates usually won’t rise, particularly if you're a long-term policy holder. If you’ve made several such claims, however, the agency may conclude you’re a greater risk than previously thought and raise your rates accordingly.