Wis. Stat. § 632.26
When the insurer denied coverage within the time that the insured could have submitted her proofs in response to the insurer's request for more information, the insurer waived the defense of lack of notice. Ehlers v. Colonial Penn Insurance Co. 81 Wis. 2d 64, 259 N.W.2d 718 (1977). The failure of policyholders to give notice to an underinsurer of a settlement between the insured and the tortfeasor does not bar underinsured motorist coverage in the absence of prejudice to the insurer. There is a rebuttable presumption of prejudice when there is a lack of notice, with the burden on the insured to prove by the greater weight of the evidence that the insurer was not prejudiced. Ranes v. American Family Mutual Insurance Co. 219 Wis. 2d 49, 580 N.W.2d 197 (1998), 97-0441. Wisconsin's notice-prejudice statutes, this section and s. 631.81, do not supersede the reporting requirement specific to claims-made-and-reported policies. Anderson v. Aul, 2015 WI 19, 361 Wis. 2d 63, 862 N.W.2d 304, 13-0500.