California SB 351: Is Your MSO Structure Illegal?

If your California med spa or aesthetic platform still uses a percentage-based MSO fee, this is no longer something to clean up later. It is a decision-point issue now.

SB 351 and AB 1415 directly affect physician-owned med spas, aesthetic practices using MSO structures, private equity-backed platforms, and any entity with contractual influence over clinical decisions. The law is enacted and in effect as of January 1, 2026.

That doesn't mean every California MSO is automatically illegal. It does mean the room for aggressive control, revenue-based compensation, and weak separation between business operations and medical authority has narrowed significantly.

SB 351 Is Going After Control, Not Just Ownership

The real focus of SB 351 is who actually influences the clinical side of the business. Private equity firms and hedge funds may not control or direct the clinical decisions and actions of physicians. Management companies may not participate in billing, coding, equipment selection, or clinical staff oversight in ways that influence physician judgment. MSO agreements may not contain language that allows or implies investor or MSO influence over clinical judgment, staffing, medical records, or patient care decisions.

California is no longer satisfied with a structure that looks compliant only on paper — it's paying closer attention to whether the MSO is actually staying in a real administrative lane.

The Compensation Model Is Now a Major Red Flag

Compliant MSO compensation must use a flat or fixed fee based on the fair market value of administrative services, and those fees must not be tied to clinical revenue, patient volume, or collections.

This is a major issue for older arrangements built around percentage-based management fees. If your MSO is still paid based on what the clinical side earns, the problem is no longer theoretical.

California Still Allows MSOs, But the Lane Is Much Narrower

SB 351 does not eliminate the MSO model — it limits what the management side can safely do and how it can be compensated. An MSO can still support infrastructure, operations, and non-clinical functions. Once it begins influencing physician staffing, shaping medical workflows through coding or billing pressure, or using contract language that gives the business side leverage over patient care, the structure starts moving into dangerous territory.

Updating the Agreement Is Not Enough If the Real Structure Is Weak

Some businesses will treat SB 351 as a contract cleanup project. That's too narrow. The recommended actions include:

• Audit all MSO agreements immediately
• Remove language implying clinical control
• Restructure compensation to flat or fixed FMV-based fees
• Review investor and lender agreements for CPOM compliance
• Strengthen telehealth protocols and medical director agreements

If the agreement says the MSO only provides administrative services but the day-to-day relationship suggests the business side is steering the practice, revised drafting alone won't solve the problem.

AB 1415 Adds Another Layer of Pressure

Under AB 1415, MSOs, private equity groups, and hedge funds are now treated as "noticing entities" under the Health Care Quality and Affordability Act. Written notice to the Office of Health Care Affordability (OHCA) is required at least 90 days before certain material transactions, including mergers, acquisitions, affiliation agreements, and other major structural changes — including those involving med spa practices.

Enforcement Is No Longer a Background Concern

The Attorney General may seek injunctive relief and recover enforcement costs for violations. Physicians in non-compliant arrangements risk discipline from the California Medical Board, and MSOs or PE-backed entities may face civil liability and regulatory sanctions.

What California Operators Should Be Reviewing Right Now

• Is the MSO still being paid as a percentage of revenue, collections, or patient volume?
• Does the agreement imply control over staffing, medical records, or patient care?
• Does the management side influence billing, coding, equipment selection, or clinical supervision in ways that could affect physician judgment?
• Do investor or lender agreements create indirect CPOM risk?
• Are telehealth protocols and medical director arrangements strong enough for California's stricter 2026 posture?

If the answer to any of those is yes, the structure deserves immediate attention.

The Bottom Line

SB 351 doesn't automatically make every California MSO structure illegal — but it makes some older models much harder to defend. A compliant MSO structure in 2026 needs to look more administrative, more clearly separated, and much less economically tied to clinical revenue than many legacy arrangements were built to be.