28 CCR §1300.71(i)(1-2)

(1) Late payment on a complete claim for emergency services and care, which is neither contested nor denied, shall automatically include the greater of $15 for each 12-month period or portion thereof on a non-prorated basis, or interest at the rate of 15 percent per annum for the period of time that the payment is late.

(2) Late payments on all other complete claims shall automatically include interest at the rate of 15 percent per annum for the period of time that the payment is late.