(1)    Unless otherwise provided by law, an insurer shall promptly pay every insurance claim. A claim shall be overdue if not paid within 30 days after the insurer is furnished written notice of the fact of a covered loss and of the amount of the loss. If such written notice is not furnished to the insurer as to the entire claim, any partial amount supported by written notice is overdue if not paid within 30 days after such written notice is furnished to the insurer. Any part or all of the remainder of the claim that is subsequently supported by written notice is overdue if not paid within 30 days after written notice is furnished to the insurer. Any payment shall not be deemed overdue when the insurer has reasonable proof to establish that the insurer is not responsible for the payment, notwithstanding that written notice has been furnished to the insurer. For the purpose of calculating the extent to which any claim is overdue, payment shall be treated as being made on the date a draft or other valid instrument which is equivalent to payment was placed in the U.S. mail in a properly addressed, postpaid envelope, or, if not so posted, on the date of delivery. All overdue payments shall bear simple interest at the rate of 7.5 percent per year.

   (2)   Notwithstanding sub. (1), the payment of a claim shall not be overdue until 30 days after the insurer receives the proof of loss required under the policy or equivalent evidence of such loss. The payment of a claim shall not be overdue during any period in which the insurer is unable to pay such claim because there is no recipient who is legally able to give a valid release for such payment, or in which the insurer is unable to determine who is entitled to receive such payment, if the insurer has promptly notified the claimant of such inability and has offered in good faith to promptly pay said claim upon determination of who is entitled to receive such payment.

   (2m)   

      (a)    Notwithstanding subs. (1) and (2) and except as provided in par. (b), a claim for payment for chiropractic services is overdue if not paid within 30 days after the insurer receives clinical documentation from the chiropractor that the services were provided unless, within those 30 days, the insurer provides to the insured and to the chiropractor the written statement under s. 632.875 (2).

      (b)    Paragraph (a) does not apply to any of the following:

         1.    Worker’s compensation insurance.

         2.    Any line of property and casualty insurance except disability insurance. In this subdivision, “disability insurance” does not include uninsured motorist coverage, underinsured motorist coverage, or medical payment coverage.

   (3)   This section applies only to the classes of claims enumerated in s. 646.31 (2).