Once an auto policy is in force, a California insurer cannot drop it at will. The California amendatory endorsement on a personal auto policy limits the reasons and sets the notice periods.

Permitted reasons: Insurance Code §661 makes a cancellation notice effective only if it rests on a listed reason, such as nonpayment of premium, fraud in a claim, a substantial increase in the hazard insured against, or suspension or revocation of a driver's license or registration. Section 1861.03(c)(1) also names nonpayment, fraud or material misrepresentation, and a substantial increase in the hazard, and it reaches nonrenewal as well as cancellation. A claim for an accident the insured did not cause is not a permitted reason.

A second chance: under §661(a)(4), an insured who negligently misrepresented information can avoid cancellation by furnishing corrected information within 20 days after receiving the notice and agreeing to pay the premium difference for the period the information was undisclosed. A correction with no extra premium is not enough.

Notice periods: - Cancellation (§662): at least 20 days before the effective date, or at least 10 days for nonpayment of premium, with the reason stated. - Nonrenewal (§663): a written notice at least 30 days before expiration. An offer of renewal must be sent at least 20 days before expiration. If a nonrenewal notice is late, the existing policy stays in effect for 30 days from the date the notice was delivered or mailed, unless the insured buys a replacement policy sooner.