Enrolling in Medicare as a CRNA or Group

To bill Medicare, a CRNA enrolls through PECOS (or paper CMS-855 forms) under an individual Type 1 NPI, and a group enrolls separately under a Type 2 NPI. Enrollment gives you a billing effective date; without it, Medicare claims deny.

The process is free, mostly online, and slower than it should be. Here is the sequence, the forms, and the maintenance rules that trip people up.

Step 1: NPI first

Everything starts with a National Provider Identifier from NPPES (nppes.cms.hhs.gov), which is free and usually issued within days:

• Type 1 NPI: you as an individual. Every CRNA needs one; you keep it for life across every job.
• Type 2 NPI: an organization, such as your LLC, professional entity, or group. A solo CRNA who forms an entity that will bill typically needs both types.

On claims, the rendering provider is your Type 1 NPI, and the billing provider is whichever enrolled entity collects payment.

Step 2: the enrollment applications

Enrollment runs through PECOS, CMS's online system, or the equivalent paper forms. PECOS is faster and lets you track status. The applications:

• CMS-855I: enrollment for individual physicians and non-physician practitioners, including CRNAs. This is your form as an individual, whether you bill for yourself or reassign your billing rights.
• CMS-855B: enrollment for clinics and group practices, filed under the group's Type 2 NPI and tax ID.
• CMS-855R: historically the separate reassignment form. CMS merged it into the revised CMS-855I in 2023, so reassignment information is now reported on the 855I (PECOS walks you through it). You may still see the 855R referenced in older guides.
• CMS-855O: for practitioners who only order and refer, and do not bill. Rarely the right choice for a CRNA.

Reassignment means authorizing your employer or group to bill and receive payment for your services. An employed or group CRNA enrolls individually and reassigns benefits to the group; the money follows the reassignment.

Your application goes to your Medicare Administrative Contractor (MAC), the regional contractor that processes enrollment and claims for your state. Processing commonly takes several weeks to a few months; applications with missing information go back for development, which restarts the clock, so complete and accurate beats fast and sloppy.

Step 3: assignment and effective dates

CRNAs are required to accept Medicare assignment, meaning the allowed amount is payment in full (Medicare's 80 percent plus the patient's 20 percent). Details on how payment works: CRNA Medicare reimbursement.

Medicare generally allows retrospective billing back to an effective date that can precede the application by a limited period (commonly up to 30 days) when requirements were met, so file before you start if at all possible, and ask your MAC how your effective date will be set.

For new groups

Launching a CRNA group? The order of operations:

1. Form the entity and get its EIN
2. Get the Type 2 NPI
3. Enroll the group with CMS-855B in PECOS
4. Each CRNA enrolls or updates with CMS-855I and reassigns benefits to the group
5. Set up EFT (CMS-588) so payments deposit to the group account
6. Run commercial credentialing in parallel, since it takes longer

Maintenance: revalidation and updates

Enrollment is not one and done:

• Revalidation: Medicare requires providers and suppliers to revalidate enrollment periodically, generally every five years. You get a due date (check it in PECOS or your MAC's lookup tool); missing it can deactivate your billing.
• Report changes: changes of ownership, practice address, bank account, or adverse legal actions must be reported, many within 30 or 90 days depending on the change.
• Deactivation: not billing Medicare for an extended period can deactivate your enrollment, requiring reactivation before you bill again.

Keep your PECOS login (via Identity & Access Management) working and your email current, because missed revalidation notices are a classic way billing stops cold.

Quick answers

Does Medicare enrollment cost anything for a CRNA?

Individual practitioners enrolling with the 855I do not pay the Medicare application fee; that fee applies to institutional providers and certain suppliers.

Do I need to re-enroll when I change jobs?

You keep your individual enrollment and Type 1 NPI, but reassignments must be updated: end the old group's reassignment and add the new one through PECOS.

Can I bill Medicare while my application is pending?

No, you cannot be paid before you have an effective date. Retrospective billing rules may cover a short window before approval; hold claims and confirm your effective date with your MAC.

What is the difference between PECOS and NPPES?

NPPES issues NPIs; PECOS handles Medicare enrollment. You need the NPI before PECOS, and the two records should match exactly.

Sources

• CMS, Medicare Provider and Supplier Enrollment (PECOS)
• CMS, Form CMS-855I, Medicare Enrollment Application for Physicians and Non-Physician Practitioners
• CMS, bulletin on consolidation of the CMS-855R into the CMS-855I (2023)
• CMS, Medicare Enrollment Revalidation
• NPPES, National Plan and Provider Enumeration System