(a) In this chapter, “net contribution” of a party to a joint account at any given time is the sum of all deposits made to that account by or for the party, less all withdrawals made by or for the party that have not been paid to or applied to the use of any other party, plus a pro rata share of any interest or dividends included in the current balance of the account. The term also includes any deposit life insurance proceeds added to the account by reason of the death of the party whose net contribution is in question.
(b) A financial institution may not be required to inquire, for purposes of establishing net contributions, about:
(1) the source of funds received for deposit to a multiple-party account; or
(2) the proposed application of an amount withdrawn from a multiple-party account.