“An account stated is an agreement, based on the prior transactions between the parties, that the items of the account are true and that the balance struck is due and owing from one party to another. When the account is assented to, ‘“it becomes a new contract. An action on it is not founded upon the original items, but upon the balance agreed to by the parties....” Inquiry may not be had into those matters at all. It is upon the new contract by and under which the parties have adjusted their differences and reached an agreement.’” (Gleason v. Klamer (1980) 103 Cal.App.3d 782, 786–787 (citations omitted).)

“An account stated need not cover all the dealings or claims between the parties. There may be a partial settlement and account stated as to some of the transactions.” (Gleason, supra, 103 Cal.App.3d at p. 790, (citation omitted).)

“The essential elements of an account stated are:

1. previous transactions between the parties establishing the relationship of debtor and creditor;
2. an agreement between the parties, express or implied, on the amount due from the debtor to the creditor;
3. a promise by the debtor, express or implied, to pay the amount due.”

(Zinn v. Fred R. Bright Co. (1969) 271 Cal.App.2d 597, 600.)

How to Structure the Motion

“The agreement of the parties necessary to establish an account stated need not be express and frequently is implied from the circumstances. In the usual situation, it comes about by the creditor rendering a statement of the account to the debtor.” (Zinn v. Fred R. Bright Co. (1969) 271 Cal.App.2d 597, 600.)

“If the debtor fails to object to the statement within a reasonable time, the law implies his agreement that the account is correct as rendered.” (Fred R. Bright Co. (1969) 271 Cal.App.2d 597, 600.)

Response

“The account stated may be attacked only by proof of ‘fraud, duress, mistake, or other grounds cognizable in equity for the avoidance of an instrument.’ The defendant ‘will not be heard to answer when action is brought upon the account stated that the claim or demand was unjust, or invalid.’” (Gleason v. Klamer (1980) 103 Cal.App.3d 782, 786–787.)