Insurer shall provide notice if a claim is a clean claim within 30 processing days of receipt of a claim and insurer shall notify a provider of all known reasons that prevented the claim for being a clean claim, if applicable. If a claim is not paid within 45 processing days from the date of receipt of the claim, the payment is subject to a 1% interest per month and a penalty in an amount equal to one percent of the claim per day.

Link to Existing Law: MO R.S. Title 12 Chapter 376 section 376.383

While PBMs are not specifically mentioned, they are likely included in the broad definition of applicable entities.