CA Food & Agric Code Section 56620

Under a contract for the purchase or handling of any farm products, any delinquent payment of money under this chapter shall also include a late charge of 5 percent per month of the unpaid balance calculated on a daily basis for the period of the delinquency for the first month and an additional 1 percent per month of the unpaid balance calculated on a daily basis for the remaining period of the delinquency. Any such late charge shall be payable to the person from whom the farm product was purchased, unless the person waives, in writing, his right to such payment. Such waiver shall be valid and effective only when given after a delinquency has occurred.

This section does not affect the time of payment provided for in this chapter or in any contract for the purchase or handling of any farm product.