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NPI for Group Practices: Enrollment and Billing Rules

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Group practices have two NPI levels: the organization’s Type 2 NPI and each individual provider’s Type 1 NPI. Understanding how these interact on claims is essential for clean Medicare billing.

This page covers the enrollment structure, billing rules, and the connection between NPIs and the Medicare enrollment forms (CMS-855I, CMS-855B, CMS-855R) that make group billing work.

The group practice NPI structure

A typical group practice Medicare enrollment looks like this:

Group Practice (Type 2 NPI: 1234567890)
  ↕ CMS-855B enrollment
  ↕
  Individual Provider A (Type 1 NPI: 9876543210)
    ↕ CMS-855I enrollment
    ↕ CMS-855R reassignment → Group
  
  Individual Provider B (Type 1 NPI: 1111111111)  
    ↕ CMS-855I enrollment
    ↕ CMS-855R reassignment → Group

Each layer requires its own enrollment:

  • The group practice files CMS-855B to get enrolled under the group’s Type 2 NPI
  • Each individual provider files CMS-855I to establish their own Medicare billing privileges
  • Each individual provider files CMS-855R to reassign their payment rights to the group

Without all three layers in place, the group cannot bill Medicare for a specific provider’s services.

How NPIs appear on claims

Under Medicare’s billing rules, group practices typically submit claims with:

  • Billing NPI: The group’s Type 2 NPI — the entity receiving payment
  • Rendering NPI: The individual provider’s Type 1 NPI — the person who performed the service
  • Referring NPI: The referring provider’s Type 1 NPI (when applicable)

Example claim line:

  • Service: 97110 (therapeutic exercise, 1 unit)
  • Rendering provider: Dr. Jane Smith, NPI 9876543210
  • Billing provider: Smith Physical Therapy LLC, NPI 1234567890

Medicare pays the group (billing NPI), and the group pays the individual provider per their employment or contractor agreement.

When you use the individual NPI vs. group NPI

Use the group NPI (Type 2) as billing NPI when:

  • The provider is employed by or contracting with the group
  • A CMS-855R reassignment is in place linking the provider to the group
  • The group has an active CMS-855B enrollment

Use the individual NPI (Type 1) as billing NPI when:

  • The provider is in solo practice (no group enrollment)
  • There is no CMS-855R reassignment to a group
  • The individual wants to bill independently for certain services

⚠️ Mixing these up causes claim denials. If a provider’s reassignment is to Group A but claims are submitted billing under Group B’s NPI (where there’s no CMS-855R), Medicare will deny the claims.

Supervising and incident-to billing

Some therapy and other services can be billed under a supervising provider’s NPI using “incident-to” rules:

Incident-to billing: Services of an auxiliary provider (such as a physical therapy assistant) can be billed incident-to the supervising PT’s NPI if the service meets incident-to requirements. This typically means:

  • The supervising provider is present in the suite during the service
  • The service is part of an established treatment plan
  • The auxiliary provider is employed by or contracted with the practice

Incident-to billing uses the supervising provider’s NPI as the rendering provider NPI on the claim. This is not a group billing concept per se — it’s a supervision billing concept.

Important: Incident-to rules are different from reassignment. Understand both and don’t conflate them.

Multi-location groups: NPI considerations

For groups with multiple practice locations:

Single entity, multiple locations: One Type 2 NPI covers all locations of the same legal entity. Include all locations in the CMS-855B enrollment. Claims from all locations use the same group Type 2 NPI.

Multiple legal entities: If locations operate under different legal entities (different EINs, different business names), each legal entity needs its own Type 2 NPI and CMS-855B enrollment.

“Provider-based” billing: If a hospital or health system owns a group practice and bills outpatient services as provider-based, the billing structure uses the facility’s NPI and requires specific CMS provider-based designation. This is not standard group practice billing and has specific regulatory requirements.

Adding a new provider to the group

When a new individual provider joins a group:

  1. Confirm the provider’s Type 1 NPI is active in NPPES
  2. Provider files CMS-855I (or confirm existing enrollment is active)
  3. Provider files CMS-855R — reassigns benefits to the group’s NPI/PTAN
  4. MAC processes the reassignment — 30–60 days typically
  5. After reassignment approval: Group can bill Medicare under the group NPI for that provider’s services

⚠️ Don’t bill under the group NPI for a new provider before the CMS-855R is approved. Claims submitted under the group NPI for a provider without an active reassignment will be denied.

Removing a provider from the group

When a provider leaves:

  1. File a CMS-855R termination — either the provider or the group files to terminate the reassignment
  2. Effective date: The termination is effective on the date specified (not retroactive)
  3. After termination date: Do not submit claims under the group NPI for that provider’s services

⚠️ Claims for dates of service after the provider left but before the CMS-855R termination is effective can be a compliance problem. File the termination promptly when a provider departs.

Questions about group NPI billing rules or adding/removing providers from your group? Ask Mae → Free Metolius Health enrollment audit →