Ask to see a copy of the certificate of insurance, or ask for the name of the contractor’s insurance carrier and agency to verify that the contractor has the insurance.

In California, if a contractor has employees, they’re required to carry workers’ compensation insurance. The importance of this cannot be overstated. If a worker is injured working on your property and the contractor doesn’t have insurance, you could be liable to pay for injuries and rehabilitation. Your homeowner’s insurance may or may not cover those costs. You should check with your insurance carrier to make sure the workers’ compensation insurance coverage being provided by the contractor is adequate. Learn more from the California Department of Insurance.

Commercial general liability insurance is not required, however, it covers damage to your property. If the contractor does not carry general liability insurance, they should be able to explain how they would cover losses that would ordinarily be covered by insurance. If your contractor damages your property and doesn’t carry commercial general liability insurance, you or your insurance policy could end up paying for damages.
A licensed contractor must provide you with information regarding both types of insurance in your written contract.