MedicaidReimbursementHigh impact
[California] New combined reimbursement policy: Modifiers 90 and 91: Laboratory Services
Anthem BCBS·CA · Pathology·Claims & Billing
Effective date
Dec 1, 2026
We identified it
Sep 2, 2026
Summary
Anthem Blue Cross Medi-Cal is implementing a new combined reimbursement policy for laboratory modifiers 90 and 91 effective December 1, 2026. Modifier 90 (pass-through lab billing) will no longer be reimbursed except in specific circumstances (outside lab services billed by another provider using HCPCS S3620 or CPT 81528, or pathology services). Modifier 91 (repeat lab tests) remains eligible for reimbursement at 100% of fee schedule. The existing modifier 91 policy (G-06020) will be retired and consolidated into the new policy (G-20001).
Action Required
By November 15, 2026: Billing team must update billing system rules and provider documentation to implement new modifier 90/91 policy. (1) Configure system to deny reimbursement for modifier 90 claims EXCEPT when billed by outside laboratory providers using HCPCS S3620 or CPT 81528, or by pathology providers. (2) Remove modifier 90 from standard laboratory service workflows unless outside lab exception applies. (3) Verify modifier 91 claims continue to process at 100% reimbursement without interruption. (4) Update all internal billing guidelines, encounter forms, and provider training materials to reflect policy change. (5) Notify all affected providers and outpatient facilities of the new requirements. (6) Do NOT balance bill members based on this policy change. Claims not complying with the new modifier 90 restrictions will be denied effective December 1, 2026.