Wis. Stat. § 628.46
Receipt of a legally binding offer to settle a claim against the insured is not required for the insured to have a claim against the insurer for bad-faith failure to settle. Alt v. American Family Mutual Insurance Co., 71 Wis. 2d 340, 237 N.W.2d 706 (1976). An insured may bring a tort action against an insurer for failure to exercise good faith in settling the insured's claim. This section is unrelated to such a tort action. Anderson v. Continental Insurance Co., 85 Wis. 2d 675, 271 N.W.2d 368 (1978). The tort of bad faith handling of a claim is discussed. Davis v. Allstate Ins. Co., 101 Wis. 2d 1, 303 N.W.2d 596 (1981). A third-party claimant cannot assert a bad faith claim against an insurer. Kranzush v. Badger State Mutual Casualty Co., 103 Wis. 2d 56, 307 N.W.2d 256 (1981). This section applies to service insurance corporations. Physicians Service Insurance Corp. v. Mitchell, 114 Wis. 2d 338, 338 N.W.2d 326 (Ct. App. 1983). A jury's imposition of punitive damages and finding of bad faith is adequate to show that the insurer did not have reasonable proof that it was not responsible for a claim and supports an award of prejudgment interest under sub. (1). Upthegrove v. Lumbermans Mutual Insurance Co., 146 Wis. 2d 470, 431 N.W.2d 689 (Ct. App. 1988). Interest under s. 807.01(4) is not in addition to interest under sub. (1). Upthegrove v. Lumbermans Insurance Co., 152 Wis. 2d 7, 447 N.W.2d 367 (Ct. App. 1989). This section makes no distinction between the payment of claims based on judgments and all other claims; a claim may be due under sub. (2) far in advance of a judgment or award. Fritsche v. Ford Motor Credit Co., 171 Wis. 2d 280, 491 N.W.2d 119 (Ct. App. 1992). Whether to assess 12 percent [now 7.5 percent] interest is dependent on whether the insurer had reasonable proof establishing that it was not responsible for payment. U.S. Fire Insurance Co. v. Good Humor Corp., 173 Wis. 2d 804, 496 N.W.2d 730 (Ct. App. 1993). This section applies to the insurance company of a negligent tortfeasor and, thus, allows the recovery of interest by a third-party claimant. When there is clear liability, a sum certain owed, and written notice of both, the plain language of this section, incorporating by reference s. 646.31(2), imposes 12 percent [now 7.5 percent] simple interest on overdue payments to third-party claimants. Kontowicz v. American Standard Insurance Co. of Wisconsin, 2006 WI 48, 290 Wis. 2d 302, 714 N.W.2d 105, 03-2177. An insurer's subrogation interest did not permit it to step into the insured's shoes to assert a 12 percent [7.5 percent] interest claim under the facts and circumstances of the case. Legal subrogation gives indemnity only, and an insurer who possesses a cause of action for subrogation cannot recover beyond the amount actually dispersed by it. Zurich American Insurance Company v. Wisconsin Physicians Services Insurance Corp., 2007 WI App 259, 306 Wis. 2d 617, 743 N.W.2d 710, 06-2320. "Reasonable proof" in sub. (1) means that amount of information that is sufficient to allow a reasonable insurer to conclude that it may not be responsible for payment of a claim. Generally, reasonable proof is equated with whether coverage is considered "fairly debatable." An insurer should not have been penalized for exercising its right to litigate when policy language was ambiguous, the court of appeals was divided on the question of coverage, the issue of coverage was one of first impression in this state, and administrative rules were subsequently modified to clarify required coverage. Froedtert Memorial Lutheran Hospital, Inc. v. National States Insurance Co., 2009 WI 33, 317 Wis. 2d 54, 765 N.W.2d 251, 07-0934. This section is limited to situations where an insurer fails to pay an insurance claim within 30 days. In this case an insurer failed to pay a contractual settlement of an insurance claim within 30 days. There is no authority for the proposition that this section can apply when an insurer fails to pay an amount required by a settlement agreement resolving a disputed claim. Singler v. Zurich American Insurance Co., 2014 WI App 108, 357 Wis. 2d 604, 855 N.W.2d 707, 14-0391. The purpose of this section is to discourage insurance companies from creating unnecessary delays in paying claims and to compensate claimants for the value of the use of their money. If the insurer has "reasonable proof" that it is not responsible, the statute does not apply. Reasonable proof of nonresponsibility is equated with whether the "coverage issue was fairly debatable." Dilger v. Metropolitan Property & Casualty Insurance Co., 2015 WI App 54, 364 Wis. 2d 410, 868 N.W.2d 177, 14-1851. When damages are high and policy limits are low by comparison, the potential for contributory negligence by a party is not, in itself, sufficient to constitute reasonable proof that will defeat an award of interest. The reasonable proof exception is satisfied when there is evidence sufficient to make a reasonable insurer conclude that it may not be responsible for payment. In this case there was no reasonable view that any contributory negligence by actors other than the defendant would have reduced the defendant insurer's liability below its policy limits. Casper v. American International South Insurance Co., 2017 WI App 36, 376 Wis. 2d 381, 897 N.W.2d 429, 15-2412. The policy behind this section is equally applicable to single or multiple-insured situations. It is not to punish insurance companies, but to compensate claimants for the time value of their money. Casper v. American International South Insurance Co., 2017 WI App 36, 376 Wis. 2d 381, 897 N.W.2d 429, 15-2412. Under Kontowicz, 2006 WI 48, a third-party claimant is entitled to prejudgment interest under this section when the amount of the damages is in a sum certain amount. The sum certain condition is not satisfied when a third-party claimant relies upon an assertion of general damages to support a demand that an excess insurer pay a specific amount, and the insurer reasonably concludes it is not certain the amount demanded is the amount the insurer may actually owe the claimant. Although, in this case, the plaintiff clearly demanded that the insurer pay a sum certainthe insurer's $1,000,000 policy limitthat sum was not reasonably demonstrated to be owed to the plaintiff by the insurer. Estate of Payette v. Marx, 2020 WI App 2, 390 Wis. 2d 356, 938 N.W.2d 628, 18-0627. This section applies to all insurers. Allison v. Ticor Title Ins. Co., 979 F.2d 1187 (1992). Excess liability insurance. Griffin. 62 MLR 375 (1979).