Every California employer except the state must secure the payment of compensation (Labor Code §3700). There is no minimum number of employees, so a bakery with one part-time counter clerk must have coverage.

Some workers fall outside the definition of employee in §3352(a), so the law does not require coverage for them. Examples include household help working under 52 hours in the 90 days before the injury, unpaid volunteers for a nonprofit, and household help employed by a parent.

Methods allowed by §3700: - insurance from an insurer authorized to write compensation in California; - a certificate of consent to self-insure from the Director of Industrial Relations, either as an individual employer or as one employer in a group. The certificate requires proof of ability to self-insure and to pay compensation. A reserve account with no certificate is not self-insurance under the law, however much money is in it.