California Civil Code 1526

(a) Where a claim is disputed or unliquidated and a check or draft is tendered by the debtor in settlement thereof in full discharge of the claim, and the words "payment in full" or other words of similar meaning are notated on the check or draft, the acceptance of the check or draft does not constitute an accord and satisfaction if the creditor protests against accepting the tender in full payment by striking out or otherwise deleting that notation or if the acceptance of the check or draft was inadvertent or without knowledge of the notation.