State v. Town of Linn
In State v. Town of Linn, 205 Wis. 2d 426, 441, 556 N.W.2d 394 (Ct. App. 1996), the Court stated that certain actions and statements on behalf of the Village of Williams Bay collectively made it clear that the village did not intend to resolve the matter before litigation and thereby disallowed the claim. See 205 Wis. 2d at 440-441.
The "statements" referred to included a letter. See id.
Linn therefore required a writing to disallow a claim. That writing post-dated the state's claim. See id. at 439, 441.