MedicaidBilling CodesMedium impact
Reminder Regarding Hospital Use of Modifier 90 for Reference (Outside) Laboratory Services
Illinois Medicaid - HFS·IL · Pathology·Provider Notice
Effective date
Jun 1, 2018
We identified it
Jun 20, 2026
Summary
Illinois hospitals must use modifier 90 when billing outpatient laboratory services performed by outside reference laboratories for Medicaid and HealthChoice Illinois patients. Many hospitals are not following this requirement and must void incorrectly billed claims and resubmit with proper modifiers.
Action Required
Immediately: Illinois hospitals must review all outpatient laboratory claims since June 1, 2018 and identify claims missing modifier 90 for outside reference lab services. Use modifier TC for in-hospital lab work and modifier 90 for outside reference labs. Prepare claim adjustments to void incorrectly billed paid claims and resubmit with appropriate modifiers using self-disclosure protocol in All Providers Handbook Supplement.