Cancellation is when a policy is ended before its term is over. Non-renewal is when it simply is not renewed at the end of the term. The California Department of Insurance defines both in its auto guide, and for auto policies the Insurance Code treats them under different rules.
Cancellation: limited reasons, notice before it takes effect
Insurance Code §661 says a notice of cancellation is effective only for a listed reason: nonpayment of premium; a suspended or revoked driver's license or vehicle registration of the named insured or a driver who lives in the household or usually drives the insured car, during the policy period or the 180 days before it took effect (or, for a renewal, before its last anniversary); fraud in pursuing a claim; material misrepresentation (with a 20-day chance to correct it) of safety record, annual miles, years of driving experience, or prior claims; or a substantial increase in the hazard insured against. Section 662 requires the notice to be mailed or delivered at least 20 days before the cancellation date, or at least 10 days when the reason is nonpayment of premium. Unless the reason is in the notice, the notice must say the insured can ask in writing for the reason, no later than 15 days before the effective date; under §666 the insurer then has 5 days to give the reason in writing.
Non-renewal: different timing, no reason list
Both of those sections say they do not apply to non-renewal. Section 663 instead requires the insurer, before expiration, to send either an offer to renew at least 20 days before expiration (written or verbal, contingent on payment) or a written notice of non-renewal at least 30 days before expiration. If the insurer sends neither, the existing policy stays in effect on the same terms for 30 days from the date a notice or offer is delivered or mailed, and it ends earlier if you buy a replacement policy for the same car.
Why the difference matters
A cancellation notice that does not match one of the listed reasons is not effective. A non-renewal needs no listed reason, but it needs the 30-day notice. In both cases the date coverage ends is what matters for registration: a gap can trigger a DMV lapse, see reinstating cancelled car insurance and insurance lapse and registration suspension. These sections are the auto rules; homeowners and business policies follow different rules, see homeowners insurance after non-renewal. Spanish: cancelación vs no renovación. Index: glossary.
Sources, checked October 9, 2026: Insurance Code §661, §662, §663; §666; CDI automobile insurance guide (common terms). The legislature's own site (leginfo) refused automated access on October 9, so the statute text was read on the Justia mirror of the California codes. Confirm the current wording on leginfo before relying on a section number in a dispute.