California Code, Civil Code - CIV § 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.

(b) Notwithstanding subdivision (a), the acceptance of a check or draft constitutes an accord and satisfaction if a check or draft is tendered pursuant to a composition or extension agreement between a debtor and its creditors, and pursuant to that composition or extension agreement, all creditors of the same class are accorded similar treatment, and the creditor receives the check or draft with knowledge of the restriction.

A creditor shall be conclusively presumed to have knowledge of the restriction if a creditor either:

(c) Notwithstanding subdivision (a), the acceptance of a check or draft by a creditor constitutes an accord and satisfaction when the check or draft is issued pursuant to or in conjunction with a release of a claim.

(d) For the purposes of paragraph (2) of subdivision (b), mailing the notice by first-class mail, postage prepaid, addressed to the address shown for the creditor on the debtor's books or such other address as the creditor may designate in writing constitutes notice.