Wis. Stat. § 861.10: Waiver of right to elect; failure to elect.

(1) Right to elect may be waived. The right to elect a deferred marital property elective share amount may be waived by the surviving spouse in whole or in part. The waiver may take place before or after marriage. The waiver must be contained in a marital property agreement that is enforceable under s. 766.58 or in a signed document filed with a court described in s. 861.08 (1) (a) after the decedent’s death.

(2) Waiver of “all rights”. Unless the waiver provides otherwise, a waiver of “all rights,” or equivalent language, in the property or estate of a present or prospective spouse, or in a complete property settlement entered into because of separation or divorce, is a waiver of all rights in the deferred marital property elective share amount.

(3) Failure to elect. Failure of a surviving spouse to elect is not a transfer of property and is not a gift from the surviving spouse to the decedent spouse’s probate estate or to the beneficiaries of other transfers.