Relating to the use of extrapolation by a health maintenance organization or an insurer to audit claims.

HB 1641 prohibits health maintenance organizations (HMOs) and insurers from using extrapolation - a method to estimate results for unreviewed claims - to audit participating physicians, providers, or preferred providers. The bill requires any payment adjustments or refunds to be based solely on actual reviewed claims, not estimated totals. It directly affects healthcare providers who contract with HMOs or insurers and applies to new or renewed contracts entered on or after September 1, 2025. The law takes effect on that date, ending the practice of using statistical estimates to determine payment disputes.