(1) Police or other law enforcement - If the accident causes a personal injury or when property damage exceeds a certain dollar amount, such as $500, you are required to report the accident to police. Officers may take reports over the phone, but sometimes you have to make reports in person at the police station.
(2) Insurance company - Most auto insurance companies require their policyholders to promptly report a car accident. The time frame can be VERY short. Failure to report in time may mean the company denies you coverage.