California Code, Health and Safety Code - HSC § 1797.233

(b)(1) A ground ambulance provider shall only advance to collections the Medicare or Medi-Cal payment amount, as determined pursuant to subdivision (a), that the uninsured or self-pay patient failed to pay.

(2) The ground ambulance provider, or an entity acting on its behalf, including a debt buyer or assignee of the debt, shall not do either of the following:

(3) With respect to an uninsured patient or self-pay patient, the ground ambulance provider, or an entity acting on its behalf, including an assignee of the debt, shall not use wage garnishments or liens on primary residences as a means of collecting unpaid bills pursuant to this section.