Group Practice

Key facts

Medicare enrollment

Group enrolls with CMS-855B; clinicians reassign payment to the group

NPI types

Type 2 NPI for the group, Type 1 NPI for each clinician

Stark Law definition

42 CFR 411.352

Common structures

Single-specialty, multispecialty, health system-owned, investor-backed

What is a group practice?

Group practices range from two partners sharing an office to medical groups with thousands of clinicians across many sites. Clinicians may be owners, employees or contractors. The group handles payer contracting, billing, staffing and compliance, and pools revenue and costs under its own rules.

For payers and regulators, the group is identified by its taxpayer identification number (TIN). Professional claims list the group as the billing provider and the individual clinician as the rendering provider, so each visit links both identities.

Types of group practices

Groups are usually described by specialty mix and ownership:

• Single-specialty groups: all clinicians share one specialty, such as orthopedics, cardiology or anesthesiology.
• Multispecialty groups: primary care and specialists practice together, often with in-house imaging, laboratory or surgery services.
• Health system-owned groups: physicians are employed by, or closely affiliated with, a hospital or health system.
• Private equity or investor-backed groups: an investor-funded platform acquires practices, often in one specialty and region.
• Faculty practice plans: groups formed by the clinical faculty of an academic medical center.

Why group practices matter

The group, not the individual clinician, often makes decisions on purchasing, product preferences, payer contracts and where referrals go. Commercial teams map clinicians to groups to target accounts, payers negotiate rates at the group level, and private equity and policy analysts track roll-ups and consolidation.

Medicare programs also measure groups. The Merit-based Incentive Payment System (MIPS) allows clinicians to report as a group under a shared TIN, and CMS Doctors and Clinicians data lists the group affiliations of individual clinicians.

Group practice under the Stark Law

The Physician Self-Referral Law uses a narrower legal definition. To rely on certain exceptions, such as the in-office ancillary services exception, a practice must meet the conditions in 42 CFR 411.352, including operating as a single legal entity with at least two physician members and meeting tests on how services are furnished and how physicians are paid. A practice that calls itself a group may not qualify.