Wis. Stat. § 767.34
A trial court is not required to give effect to a property division agreement entered into before divorce proceedings are instituted. It should make its own determination of whether the agreement adequately provides for the parties. Ray v. Ray, 57 Wis. 2d 77, 203 N.W.2d 724 (1973). There are two types of postnuptial agreements: 1) family settlement agreements that contemplate the continuation of the marriage; and 2) separation agreements that are made after separation or in contemplation of separation. The former are presumed binding on the parties under s. 767.255(3) (L) [now s. 767.61(3) (L)]. The latter are governed by s. 767.10 [now this section] and constitute a recommendation jointly made by the parties to the court regarding what the judgment should provide. Evenson v. Evenson, 228 Wis. 2d 676, 598 N.W.2d 232 (Ct. App. 1999), 98-0803. See also Van Boxtel v. Van Boxtel, 2001 WI 40, 242 Wis. 2d 474, 625 N.W.2d 284, 99-0341. An agreement made in contemplation of divorce, entered into after the parties agreed to the divorce, was subject to s. 767.10 [now this section], not s. 767.255 [now s. 767.61]. When a party withdrew his consent before court approval, the agreement was unenforceable. Ayres v. Ayres, 230 Wis. 2d 431, 602 N.W.2d 132 (Ct. App. 1999), 98-3450. A trial court may refuse to incorporate a stipulation in a divorce judgment when a party repudiates his or her consent. A party is free to withdraw from a stipulation until it is incorporated in a judgment, and repudiation may render the stipulation nonexistent. Van Boxtel v. Van Boxtel, 2001 WI 40, 242 Wis. 2d 474, 625 N.W.2d 284, 99-0341. The specific language of sub. (1) controls stipulations in divorces rather than the general language of s. 807.05. All agreements entered into after a divorce is filed are stipulations subject to sub. (1) and must be approved by the court. Polakowski v. Polakowski, 2003 WI App 20, 259 Wis. 2d 765, 657 N.W.2d 102, 02-1961. A stipulation under this section is not a contract that would be binding on the parties once entered into, but is only a recommendation to the court. The court need not accept it but has a duty to decide whether that recommendation is a fair and reasonable resolution of the issues that the court wants to adopt. When a court adopts a stipulation, it does so on its own responsibility within it's discretion, and the provisions become the court's judgment. Once the court decides to do so, the right of a party to withdraw from the stipulation comes to an end. Hottenroth v. Hetsko, 2006 WI App 249, 298 Wis. 2d 200, 727 N.W.2d 38, 05-1212. Before approving a stipulation, the circuit court is not required to take evidence and make an investigation in essentially the same manner as if the stipulated matters were contested. Under the facts of this case, it was unnecessary to define the minimum requirements that must be met before a court approves a stipulation. Hottenroth v. Hetsko, 2006 WI App 249, 298 Wis. 2d 200, 727 N.W.2d 38, 05-1212.