Modifies provisions relating to MO HealthNet third party liability

SB 1687 modifies Missouri's MO HealthNet program to clarify how the state recovers payments from third parties (like insurance companies or liable entities) when they are responsible for medical costs. It establishes MO HealthNet as the "payer of last resort," requiring third parties to reimburse the state for covered services paid by MO HealthNet, with claims due within three years of service. The bill specifies that insurers must process valid subrogation claims without denying them for late submission, missing documentation, or prior authorization issues (except for Medicare plans), and limits reimbursement to amounts the insurer would have paid if billed properly. This directly affects MO HealthNet participants, healthcare providers, and third-party insurers by streamlining recovery processes and setting clear timelines.