Solo to Group Practice: The Insurance Checklist

Last reviewed: October 8, 2026.

Turning a solo practice into a group is mostly an insurance identity project. The group needs its own legal entity, EIN, and Type 2 NPI. Then every payer has to recognize that identity and connect each clinician to it, whether through a group contract or by linking individual contracts to the group’s tax ID. Medicare, direct deposit, remittances, and your EHR each need their own update. Keep billing under the old setup until each payer confirms the new one is effective.

This is the hub checklist. Where we already have a detailed guide for a step, we link to it instead of repeating it. The questions below are the ones practice owners ask us most when they add their first associate or contractor: do my contracts carry over, does each clinician need their own application, and when can we start billing under the group.

The order that avoids payment gaps

1. Form the entity your state allows for your license.

2. Get the entity’s EIN and keep the IRS letter.

3. Get a Type 2 NPI for the entity. Keep your Type 1.

4. Add the group as a practice location in each clinician’s CAQH.

5. Ask each payer how it handles a new group, then file its transaction.

6. Enroll the group in Medicare and reassign each clinician to it.

7. Add new clinicians to each payer’s roster for the group.

8. Enroll direct deposit (EFT) and remittances (ERA) under the group.

9. Set the group NPI and tax ID in your EHR.

10. Cut over payer by payer, by date of service, and let old claims finish under the old identity.

1. Choose the entity your state allows

Most group owners form a PLLC, PC, or LLC. Which one you may use depends on your state and license, so confirm it with an attorney before you file. We explain why billing under an entity beats billing under your Social Security number in Bill Under a PLLC or PC, Not Your SSN.

California is the common exception people miss. Its LLC statute does not let a domestic or foreign LLC render licensed professional services, so California therapy groups usually use a profession-specific professional corporation. Our California entity guide walks through the LMFT, LCSW, LPCC, and psychology corporation rules, and Medi-Cal group vs. individual NPI-2 rules explains why a PC’s Type 2 NPI does not automatically make it a Medi-Cal group.

2. Get the EIN and keep the IRS letter

Apply for the entity’s EIN through the IRS and save the confirmation letter. Payers increasingly ask for it. Blue Cross and Blue Shield of Illinois, for example, began requiring both a W-9 with the legal and DBA name and official IRS documentation of the tax ID (such as an SS-4 or 147C) with new-provider applications on August 1, 2026. If you cannot find yours, see how to replace a lost EIN letter.

Make the legal name identical on the W-9, the IRS letter, NPPES, CAQH, and the business bank account. If you are changing the tax ID of an entity that already bills, that is a different project; use How to Change EIN With Insurance Companies.

3. Get a Type 2 NPI for the group

Request the organization NPI in NPPES. Every clinician keeps their own Type 1 NPI as the rendering provider. The group’s Type 2 goes on claims as the billing provider. Step-by-step: How to apply for an NPI Type 2. The difference between the two: NPI Type 1 vs Type 2.

4. Add the group to each clinician’s CAQH

Many commercial payers pull credentialing data from CAQH. Aetna, for instance, says it gets your credentialing application from CAQH ProView after contracting. For the group, that means each clinician’s profile needs a practice location for the group, with the legal name and EIN exactly as on the W-9 and the group’s Type 2 NPI.

In our experience, a missing group location is a silent failure: the payer looks for the clinician under the group’s tax ID, finds nothing, and the application stalls without an error. Two more details matter:

• Add the group as a new location rather than editing an old one. A profile can carry more than one active location, so a clinician who is still billing elsewhere does not have to remove that affiliation first.

• Re-attest after the change and make sure payers are authorized to view the profile. Until the clinician re-attests, payers do not see the new location.

More on keeping payers in sync: Changed your practice address in CAQH? Update payers too.

5. Contract the group, or link existing contracts to it

This is where most of the work is, and it is the question owners ask most: will my existing contracts carry over to the group? Sometimes the payer links your existing participation to the new tax ID. Sometimes it requires a new group agreement. Payers handle a new group in one of two ways, and some use both depending on product or state.

Individual credentialing, linked to the group’s tax ID

Many behavioral health networks credential each clinician individually and treat the group’s tax ID as a link. Aetna’s request-for-participation page tells groups to file an individual Type 1 application, with a separate application for each provider in the group. A clinician already participating with Aetna under their SSN or an old employer’s tax ID adds the new tax ID instead of reapplying. Evernorth works similarly; see Already With Evernorth? Link Your New Group Tax ID. Optum adds a tax ID through Provider Express, and caps a clinician at four active tax IDs, so an old affiliation may have to come off first: How to Remove an Old Group TIN From Optum.

Treat individual participation and the group link as separate facts. We have seen a clinician show as active with a payer under an old name, SSN, and address while the new group’s tax ID was not linked to them at all. Ask the payer both questions: is the clinician active, and are they active under this group’s tax ID?

A group contract under the group’s tax ID

Other payers contract the group itself and then roster clinicians onto it. These contracts are not always available to a new practice. Optum says group contracts are available under limited circumstances, with criteria that include at least five credentialed providers and central intake and billing. Health Net in California keeps separate doors for a new agreement and for adding a practitioner to an existing contract, and its participation form says it is for new agreements only. Pick the wrong one and the request is misrouted.

State Medicaid programs and their managed care plans usually need their own enrollment for a new group, separate from commercial contracts. Before you file anything, ask each payer which transaction it wants for a new group and tax ID, write down the answer and reference number, and do not assume one payer’s answer applies to another.

6. Enroll the group in Medicare and reassign clinicians

Medicare needs two things: the group enrolled as an organization, and each clinician’s right to bill reassigned to it. The group enrolls on the CMS-855B. Reassignments now go on the CMS-855I, which absorbed the old CMS-855R. Both the clinician and the group must be enrolled, or enrolling at the same time, before a reassignment takes effect. The group also needs EFT on file through the CMS-588.

If you are the sole owner of a new PC, PLLC, or LLC and already enrolled as an individual, PECOS offers a sole-owner path that enrolls the organization and bundles your reassignment. Do not file a second individual enrollment for a state and specialty you are already enrolled in. A practitioner already enrolled who joins an existing group files a reassignment, not a new enrollment: Already Enrolled in Medicare? Reassign to a New Group. For the first-time setup, see how to credential Medicare as a therapist LLC.

7. Add each new clinician to the roster

Every clinician you hire repeats steps 4 to 6 for themselves: a CAQH location for the group, the payer’s add-provider or roster request, and a Medicare reassignment. Blue Cross and Blue Shield of Illinois, for example, has an add-provider path on its onboarding application that keys on the group’s tax ID and Type 2 NPI and takes a roster. Evernorth handles additions to an existing group contract through Provider Services; on one roster addition, the representative quoted up to 30 business days to link the clinician.

Pre-licensed clinicians follow different rules, and they vary by payer and state. Some payers will roster an associate; others require billing under a licensed supervisor or will not cover the service at all. Start with Who Can I Bill Under as My Supervisor? before you schedule an associate’s insurance clients.

When someone leaves, removing them is not the same as ending the group’s contract: Remove a Clinician or Terminate the Payer Contract?.

8. Re-enroll EFT and ERA under the new tax ID

Direct deposit (EFT) and electronic remittances (ERA) are enrolled per payer and tied to the tax ID and NPI that the payer pays. A new group usually means new EFT and ERA enrollments with each payer. When you change or add a tax ID, also confirm the billing (pay-to) address the payer has on file for it. We have seen payers add a tax ID without updating that address, which sends checks and correspondence to the old one.

Leave the old EFT and ERA in place until the old tax ID’s claims finish paying. Payments, take-backs, and appeals on older dates of service still flow through them. If a deposit arrives with no remittance, see ERA received but no EFT deposit and, for one payer’s steps, setting up Evernorth EFT and ERA.

9. Set the group NPI and tax ID in your EHR

Your EHR puts the billing provider on every claim, so it has to match what each payer approved.

• SimplePractice: its group practice setup guide says groups usually bill with a group NPI and tax ID, with each clinician’s Type 1 NPI as the rendering NPI, set under the billing provider information in insurance settings. It also recommends that team members billing under their own NPI and tax ID use a separate account. During a transition, claim rules can send each payer’s claims under the right tax ID.

• TherapyNotes: the practice’s Type 2 NPI is recorded in practice settings and included on all claims. Clinician billing setting overrides let a clinician bill a specific payer with different NPI or tax ID details, which is useful while some payers are still on the old setup.

• Sessions Health and others: the principle is the same. Set the billing provider per payer to the combination that payer has approved, and keep each clinician’s Type 1 NPI as the rendering provider.

Changing the tax ID in your EHR does not fix claims that were already sent. Make the change only for dates of service on or after the payer’s confirmed effective date.

10. Time the transition so old claims still pay

Payers approve a new group on different dates. In one recent conversion we handled, three commercial networks became effective under the new entity over about five weeks, and one payer’s tax ID link still needed verification after its effective date. That is normal. Plan for it:

• Keep billing each payer under the old identity until that payer confirms the new one is effective, for the clinicians and locations you need.

• Switch one payer at a time by date of service. Claims for visits before the switch stay on the old tax ID, including corrections and appeals.

• Verify benefits under the new entity before telling a client they are in network. A clinician seeing clients under the new entity still needs a plan-specific check.

• Send a small first batch of claims under the new identity and wait for the first remittance before moving everyone.

• Do not terminate old contracts, Medicare reassignments, EFT, or ERA until the old claims have paid or closed.

If you are also switching EHRs or billers, pair this with switching EHRs with unpaid claims and the biller handoff guide.

A simple tracker

Keep one row per payer and update it as answers come in. The columns that matter:

• Transaction the payer requires (link tax ID, new group contract, roster addition, Medicaid enrollment).

• Reference number and date of the instruction.

• Group effective date, and each clinician’s effective date.

• EFT, ERA, and pay-to address confirmed.

• First accepted claim and first paid claim under the group.

• Date old-tax-ID claims are finished.

Where Bomi fits

Bomi does this credentialing and billing work for group practices: CAQH locations, payer applications and tax ID links, roster additions, Medicare reassignment, EFT and ERA enrollment, and the payer-by-payer cutover in your EHR. Credentialing is $50 per insurance company per clinician, with the first four free when you choose Bomi Billing. Billing is 4% of net collections, and roster updates and ongoing credentialing are included. See how Bomi works with groups or talk to us.

Related Guides

• Bill Under a PLLC or PC, Not Your SSN

• How to apply for an NPI Type 2

• How to Change EIN With Insurance Companies

• Already Enrolled in Medicare? Reassign to a New Group

• Already With Evernorth? Link Your New Group Tax ID

• How to Remove an Old Group TIN From Optum

Frequently Asked Questions

Do my individual insurance contracts carry over to my new group?

Sometimes. Payers that credential clinicians individually, such as Aetna, Evernorth, and Optum, can usually link your existing participation to the group’s tax ID. Payers that contract the group itself may require a new group agreement, and state Medicaid programs usually need a separate group enrollment. Ask each payer which transaction it requires.

Does every clinician in the group need their own application?

With many behavioral health payers, yes. Aetna asks for a separate application for each provider in a group. Even when a payer contracts the group, each clinician still has to be added to the roster and, for Medicare, reassign their billing to the group.

Can I keep billing under my old tax ID while the group is credentialed?

Yes, and you should, payer by payer, until each one confirms the group is effective. Claims for visits before a payer’s switch date stay under the old tax ID, and old EFT and ERA enrollments should stay open until those claims finish.

Do I need an office before credentialing the group?

Applications ask for a practice location, and CAQH lets you mark a location as virtual-only for telehealth. Medicare asks for each location where you render services, including telehealth sites. Timing matters too: one Medicare contractor told us it keeps applications only when the proposed start date is within about 60 days, so do not file Medicare far ahead of opening.

Do I need a new Type 2 NPI if I already have one for my solo LLC?

Not if the same entity becomes the group. Keep its Type 2 NPI and add clinicians under it. A genuinely new entity, such as a new professional corporation, gets its own Type 2 NPI and EIN.

Sources

IRS: Get an employer identification number

CMS: NPPES

BCBSIL: Change in onboarding process for new providers, effective Aug. 1, 2026

Aetna: Join the Aetna network

Optum Provider Express: Group with individually credentialed providers

Health Net: Add to Group Form

CMS-855B: Medicare enrollment for groups

CMS-855I: Medicare enrollment and reassignment for practitioners

CMS-588: Medicare EFT authorization

SimplePractice: Setting up a group practice account

TherapyNotes: Clinician billing setting overrides