"Companies writing health insurance business in California are required to participate in the California Life and Health Insurance Guarantee Association. If a company writing health insurance becomes insolvent, the California Life and Health Insurance Guarantee Association settles unpaid claims and assesses each insurance company for its fair share."
"California law allows all companies to surcharge policies to recover these assessments. If your policy is surcharged, "CA Surcharge" with an amount will be displayed on your premium notice."
Ca. Ins. Code § 1067.08