Two Medicare enrollment records decide whether a practice gets paid: the group’s and the clinician’s. The CMS-855B creates the first, for a clinic or group practice billing Part B under its own legal business name and tax ID. The CMS-855I creates the second, for the individual physician or non-physician practitioner. File the wrong one and the Medicare Administrative Contractor returns it instead of converting it.
What this covers
- The CMS-855B enrolls the organization and requires a Type 2 NPI.
- The CMS-855I enrolls the individual practitioner under a Type 1 NPI.
- The CMS-855R was retired in 2023. Reassignment now runs through the CMS-855I or PECOS.
- CMS requires both the group and the practitioner to be enrolled before a reassignment takes effect.
The 855B enrolls the business. The 855I enrolls the clinician. A reassignment links the two, and it needs both records.CMS-855B section 4H and CMS-855I section 4F
What each application establishes
The CMS-855B enrolls the business: legal business name, tax identification number, ownership and managing control, practice locations, and the authorized official who signs for the entity. It requires a Type 2 NPI, the number assigned to an organization.
The CMS-855I enrolls a person: identity, Social Security number, licenses, specialty, and practice locations, under a Type 1 NPI. Approval issues a PTAN, the number Medicare pays that practitioner under.
| CMS-855B | CMS-855I | |
|---|---|---|
| Who it enrolls | Clinic, group practice or other supplier | Physician or non-physician practitioner |
| NPI required | Type 2 (organization) | Type 1 (individual) |
| What approval issues | Organization PTAN under the group’s TIN | Individual PTAN under the practitioner’s NPI |
| 2026 application fee | $750 for institutional filers, excluding physician and NPP organizations | None |
| Reassignment of benefits | Section 4H reports a reassignment the group accepts or terminates | Section 4F reports the reassignment the practitioner grants |
The Provider Transaction Access Number is any Medicare number other than the NPI that a practitioner bills with. Both forms also call it the Medicare supplier number or billing number.
The one question that decides which form you file
Specialty does not decide it. Headcount does not decide it. The question is which entity appears as the billing provider on the claim.
- Claim goes out under the group’s legal business name and TIN: the group files the CMS-855B, which creates the group PTAN.
- Practitioner bills under their own NPI and TIN: they file the CMS-855I.
- Both happen: you file both, and the clinician with a private practice grants a reassignment for the group work.
A sole owner sits in both seats at once. Section 4A1 of the CMS-855I covers a professional corporation, association, or LLC, including a single member LLC, and asks for the entity’s Type 2 NPI alongside the practitioner’s own. Section 4A is enough when a sole owner bills Medicare through that entity.
A sole owner who wants to name an authorized or delegated official on the enrollment does not file the CMS-855I. Page 1 of that form points to the CMS-855B instead.
Filing order and the paperwork both forms expect
The two applications can go in together. CMS writes that a group and a practitioner may enroll concurrently, and that the reassignment takes effect only once both records exist.
The organization needs an active Type 2 NPI whose legal business name and TIN match the IRS record. Each practitioner needs a Type 1 NPI with the correct taxonomy code.
The group record has to exist before anything can be reassigned to it.
Practitioners with no private practice who reassign all benefits complete section 4F only.
In section 4F, name the organization, its NPI, its PTAN if issued, and the effective date. If the practitioner is enrolling at the same time, write pending in the Medicare number block.
Licenses and certifications, the electronic funds transfer agreement with a voided check or bank letter, and IRS confirmation of the legal business name and TIN.
Before the envelope goes out
- Both applications typed, signed and dated. Neither form accepts a handwritten application.
- Certification signed within 120 days of the date the contractor receives it.
- Practitioner signs section 15B and the group official signs section 15C on a new reassignment.
- Every active reassignment listed, including reassignments established years ago.
Reassignment of benefits and the form that replaced the 855R
The CMS-855R is gone. The CMS-855I carries reassignment now, and CMS told Medicare Administrative Contractors to begin accepting that version on September 1, 2023. Older filings were accepted through October 30, 2023. From November 1, 2023, MACs return them with a letter naming the current version.
Reassignment lets a group bill for work a practitioner performed. Medicare does not pay a supplier’s claim to another party in the ordinary case, and 42 CFR 424.80 lists the exceptions, among them payment to an employer and payment to an enrolled entity under a contractual arrangement.
- A new reassignment needs two signatures: the practitioner in section 15B and a delegated or authorized official of the organization in section 15C. On the CMS-855B the matching sections are 15E and 15B or 15D.
- Terminating or changing a reassignment needs one signature, from either side.
- After a termination, reassigned claims for that practitioner are no longer paid to the group.
The CMS-855I requires revalidation applications to list all active reassignments. A reassignment left off the form leaves the group with no documented right to bill for that practitioner.
Where a wrong form costs weeks
The rejection regulation is explicit. 42 CFR 424.525(a)(1)(x) lists submitting the incorrect CMS-855 application among the reasons CMS may reject an application, and gives the filer 30 calendar days from the contractor’s request for missing information to supply it.
A rejected application is not a denied application. Rejection means the file was never entered for processing. Rejected applications carry no appeal rights, nothing converts one form into the other, and the practice must submit a complete new application under a new receipt date.
- Unsigned or undated applications, or a copied or stamped signature.
- An application signed more than 120 days before the contractor received it.
- A reassignment package missing a required form not delivered within 30 days.
- An institutional application filed without the fee or a hardship waiver.
The weeks come from the rebuild. Physicians, non-physician practitioners and their organizations may bill retrospectively for services furnished up to 30 days before their enrollment effective date under 42 CFR 424.521. Services rendered earlier than that window fall outside the allowance.
CMS returns filings made on old versions of a form. The current CMS-855I is marked 05/23 and the current CMS-855B is marked 12/2025.
Keeping both records consistent after approval
Both records revalidate on a five-year cycle under 42 CFR 424.515, and CMS contacts the practice when the window opens. The practice then has 60 calendar days to submit the application and supporting documentation. Off-cycle revalidations exist as well.
Changes run on shorter clocks. A change of ownership, an adverse legal action, or a change to a practice location is due within 30 days. Every other change, reassignment information included, is due within 90 days. The CMS-855B points groups at 42 CFR 424.516(d)(2) for reassignment changes.
- A PTAN on file for the group and for every practitioner billing under it.
- An active reassignment on the 855I record of each clinician billing through the group.
- Practice locations in PECOS matching the locations printed on claims.
- Legal business name, TIN and NPI matching across PECOS, NPPES and the IRS record.
Roster changes are the other half of the work. Terminate a reassignment when a clinician leaves, because claims stop going to the group after its effective date. When the practice’s tax ID changes, the CMS-855B requires a new application rather than an amendment. Credentialing and payer enrollment is where the group record, the individual record and the payer contracts get reconciled.
CMS-855B and CMS-855I questions
Only if two things are true. The practice bills Medicare under its own legal business name and TIN, which requires the group record the CMS-855B creates. And the clinicians are enrolling. A practitioner who bills only through the group still needs a CMS-855I record, because the reassignment runs off the individual enrollment.
No. The CMS-855R was folded into the CMS-855I, and Medicare Administrative Contractors began accepting the revised CMS-855I on September 1, 2023. Older versions were accepted through October 30, 2023. Since November 1, 2023, MACs return them. Reassignment now goes in section 4F of the CMS-855I, or in the reassignment section of PECOS.
No. CMS requires both the individual practitioner and the eligible organization or group to be enrolled, or to be enrolling at the same time, before a reassignment takes effect. A group with an active PTAN cannot submit a claim for a clinician who has no Medicare enrollment record.
Both sides. On the CMS-855I, the practitioner signs section 15B and a delegated or authorized official of the organization signs section 15C. On the CMS-855B, the matching sections are 15E and 15B or 15D. Terminating or changing a reassignment needs one signature, from either side.
Turnaround is set by your Medicare Administrative Contractor, and clean electronic filings move faster than paper. The clocks CMS publishes in regulation are 30 calendar days to answer a request for missing information, and 60 calendar days to answer a revalidation notice. Mismatched NPI, TIN or legal business name data pushes a file into a second review.
Sometimes. CMS defines an institutional provider as any provider or supplier that submits a CMS-855A, a CMS-855B (except physician and non-physician practitioner organizations) or a CMS-855S. The CY 2026 fee is $750, and it applies on initial enrollment, revalidation, and when a filer adds a practice location. Physicians and non-physician practitioners filing a CMS-855I pay nothing.
The bottom line
Two records, filed in one order, decide whether the group can bill at all. The CMS-855B enrolls the organization, the CMS-855I enrolls the clinician, and the reassignment on section 4F is what lets the group’s claim carry that clinician’s work. Get the form and the version right the first time, because a rejection restarts the file.
Which Medicare enrollment record is missing?
We handle Medicare enrollment and payer credentialing for behavioral health practices: NPI and TIN checks, the CMS-855B and CMS-855I, reassignment paperwork, PTAN tracking, and the calendar that keeps both records active. Send us your clinician roster and we will show you which PTANs and reassignments are missing. Our medical billing services team takes over the follow-up with the MAC.
Request a free credentialing auditThis article describes Medicare enrollment mechanics published in the current CMS-855 forms and in 42 CFR part 424 as of September 2026, and it is general information rather than legal advice. Confirm requirements with your MAC before filing, and read how we work for the scope of our services.
