Section 705.03 - Ownership during lifetime Unless there is clear and convincing evidence of a different intent:
(1) A joint account belongs, during the lifetime of all parties, to the parties without regard to the proportion of their respective contributions to the sums on deposit and without regard to the number of signatures required for payment. The application of any sum withdrawn from a joint account by a party thereto shall not be subject to inquiry by any person, including any other party to the account and notwithstanding such other party's minority or other disability, except that the spouse of one of the parties may recover under s. 766.70. No financial institution is liable to the spouse of a married person who is a party to a joint account for any sum withdrawn by any party to the account unless the financial institution violates a court order.(2) A P.O.D. account belongs to the original payee during the original payee's lifetime and not to the P.O.D. beneficiary or beneficiaries. If 2 or more parties are named as original payees, during their lifetimes rights as between them are governed by sub. (1); and a surviving original payee may revoke or amend the P.O.D. beneficiary designation at will.(3) A marital account belongs, during the lifetime of both parties, to the parties without regard to the proportion of their respective contributions to the sums on deposit or to the number of signatures required for payment. A party to a marital account may name one or more P.O.D. beneficiaries for that party's interest. No person may inquire about the application of any sums withdrawn from a marital account by a party to the account, except that if the parties are married to one another the other party to the account may recover under s. 766.70.1973 c. 291; 1983 a. 186; 1993 a. 486. Withdrawal of funds from a joint account by either party while both are alive may not later be subjected to inquiry by the other party's estate. Matter of Estate of Frank, 140 Wis. 2d 429, 410 N.W.2d 621 (Ct. App. 1987). The transfer of separately owned property of one spouse into a joint account in both spouses' names changes the character of the ownership interest of the entire property to marital property. In Matter of Estate of Lloyd, 170 Wis. 2d 240, 487 N.W.2d 644 (Ct. App. 1992). A guardian steps into the shoes of the ward and cannot prevent another party from withdrawing funds from a joint account. That a guardianship is established does not preclude a joint owner of an account from removing the funds. Family Services, Inc. v. Gary W. 2003 WI App 132, 265 Wis. 2d 681, 666 N.W.2d 84, 02-3139. A joint checking account established under this section prior to the execution of a power of attorney creates a presumption of donative intent. When an agent acting under a power of attorney transfers funds deposited by the principal from a joint account for the agent's own use, a presumption of fraud is created. When these two conflicting and inconsistent presumptions coexist, the circuit court is free to make a determination based upon the facts and the credibility of the witnesses. Extrinsic evidence may be admissible to determine the intent of the parties. Russ v. Russ, 2007 WI 83, 302 Wis. 2d 264, 734 N.W.2d 874, 05-2492.