California Code, Government Code - GOV § 53088.6

(a) For all contracts entered into on or after January 1, 1997, at or before the time the consumer enters into the initial agreement for services, the consumer is provided with written notice that it is the policy of the seller to impose a fee on delinquent accounts.

(b) At least 10 days prior to the date a fee is imposed, the consumer is warned on the face of the notice, in writing of the late fee that will be imposed if a consumer's delinquency is not paid.  This notice shall specify the date on or after which a late fee will be charged.

(c) The consumer's invoice specifies a due date that is not earlier than the 10th day of the service period for which the invoice is issued.

(d) The fee is assessed no earlier than 27 days after the due date specified in the invoice.

(e) The fee is assessed on a delinquent balance of more than ten dollars ($10).