The End of an Era for Incident-To Billing: BCBS Michigan Mandates SA Modifiers and Cuts VBR in Phase 1 Overhaul

As of September 1, 2026, the landscape of medical coding and billing in Michigan has fundamentally shifted. Blue Cross Blue Shield of Michigan (BCBSM) and Blue Care Network (BCN) have officially initiated Phase 1 of their highly anticipated—and fiercely debated—incident-to billing overhaul.

For years, incident-to billing has allowed services performed by non-physician practitioners—such as Physician Assistants (PAs), Nurse Practitioners (NPs), and pre-licensed behavioral health clinicians—to be billed under a supervising provider’s National Provider Identifier (NPI), capturing 100% of the physician fee schedule.

That era is coming to a close. With the rollout of Phase 1, practices must navigate strict new incident-to billing requirements, including the mandatory use of the Modifier SA HCPCS Level II code, and face the immediate elimination of Value-Based Reimbursement (VBR) eligibility for these claims.

Decoding Phase 1: The SA Modifier and the VBR Freeze

The core of the September 1, 2026 update centers on billing transparency and tracking. Any clinician eligible to enroll directly with BCBSM who continues to bill incident-to must now append Modifier SA to every applicable claim line. (While the official definition of the modifier is "Nurse practitioner rendering service in collaboration with a physician," it applies broadly to Advanced Practice Providers and supervised clinicians under this policy).

While claims appended with Modifier SA will temporarily continue to be paid at the supervising physician's applicable rate during this transition window, they are now entirely excluded from Value-Based Reimbursement (VBR) programs. This means practices instantly lose bonuses associated with the Physician Group Incentive Program (PGIP) for these specific visits.

Behavioral Health in the Crosshairs: A Threat to the Workforce Pipeline

While primary care practices are feeling the administrative squeeze, the behavioral health sector is bracing for a catastrophic financial impact. Private practices heavily rely on incident-to billing to employ limited-license clinicians (such as LLPCs and LLMSWs) who are completing their required supervised hours.

When treating patients for common mental health conditions, accurate coding is critical for demonstrating medical necessity. Whether a pre-licensed clinician is billing ICD-10 codes for mental health such as F41.1 (Generalized anxiety disorder) or F32.9 (Major depressive disorder, single episode, unspecified), the new rules apply. Even for initial intake assessments coded with Z03.89 (Encounter for observation for other suspected diseases and conditions ruled out)—used when a patient is evaluated but a definitive psychiatric diagnosis isn't confirmed—the SA modifier is now required, and the practice loses out on value-based incentives.

Because behavioral health diagnosis codes make up a massive portion of incident-to claims, mental health advocates fear this will cripple the pipeline of new therapists during a statewide mental health workforce shortage. This sparked significant pushback over the summer. On August 21, 2026, the Michigan Mental Health Counselors Association (MMHCA) and the National Association of Social Workers (NASW-Michigan) organized a major rally outside BCBSM headquarters in Detroit, demanding that the insurer reconsider removing the incident-to pathway for limited-license professionals.

The March 2027 Cliff: Phase 2 Looms Large

Phase 1 is merely a warning shot. On March 1, 2027, Phase 2 of the BCBSM policy takes effect, bringing draconian financial penalties for non-compliance.

• The 80% Penalty: By March 1, 2027, any practitioner eligible to enroll directly with BCBSM/BCN must bill under their own NPI. If a practice continues to bill incident-to using the SA modifier, reimbursement will automatically plummet to 80% of the applicable professional fee schedule.
• A Ban on Trainees in Private Practice: Students, trainees, and providers with provisional licensure will be entirely barred from utilizing incident-to billing in professional, office-based settings. Their services will only be reimbursable in facility-based settings, such as hospitals or community mental health agencies.

Advocacy and Off-Cycle Adjustments

In response to the medical community's outcry, organizations like the Michigan State Medical Society (MSMS) and the Michigan Academy of Family Physicians (MAFP) successfully negotiated minor concessions. BCBSM announced additional off-cycle value-based reimbursement opportunities for primary care Advanced Practice Providers (APPs). Beginning in January 2027, primary care APPs who were not previously participating in PGIP will have a special enrollment window to qualify for direct-NPI value-based incentives, helping some practices recoup the revenue lost during the Phase 1 transition.

Action Plan for Practices

The clock is ticking. Medical billing and coding teams must audit their EHR and clearinghouse workflows immediately to ensure the SA modifier is correctly appended to all applicable September 2026 dates of service. Furthermore, practice administrators must begin the lengthy credentialing process for eligible APPs to ensure they can bill under their own NPIs before the March 2027 deadline strikes. Failing to adapt to these new incident-to billing requirements will result in immediate VBR losses today, and devastating 20% revenue cuts tomorrow.