A four-physician orthopedic group hired a new surgeon to start in March. The office manager had never had the CMS 855I, 855B and 855R explained to her. She went to the MAC website, found a list of forms, and filled out the CMS-855B because it said "group." Six weeks later the MAC returned it: the group was already enrolled, and what the surgeon needed was an 855I and an 855R. The surgeon started seeing Medicare patients in March, and the practice held those claims until June. None of that was necessary. It happened because nobody had ever explained the forms.
So here is the CMS 855I, 855B and 855R explained in the order a practice actually uses them. Medicare enrollment describes two things: a person (the physician or non-physician practitioner) and an organization (the group practice that bills). Each has its own enrollment record. Then there is a link between them that lets the group receive payment for the individual's services. Every form in the family maps to one of those three ideas.
A glossary line: PECOS is the Provider Enrollment, Chain, and Ownership System, the online database where Medicare enrollment records live. Everything the paper forms do can be done in PECOS, and we recommend doing it there because it is faster and the status is visible. The MAC is the Medicare Administrative Contractor for your state, the company that processes the application on CMS's behalf.
Key takeaways
- The 855I enrolls a person, the 855B enrolls a group, and the 855R connects a person to a group so the group can be paid.
- A new physician joining an already enrolled group needs an 855I (if not already in PECOS) and an 855R, not an 855B.
- Medicare allows retroactive billing back to the effective date, which is the later of the filing date or the start of service, with a limited look-back.
- Revalidation is required every five years, and a missed revalidation deactivates billing without warning to the front desk.
- Almost every rejection is a mismatch between the form and the NPPES record or the IRS document, so check those first.
CMS 855I, 855B and 855R explained: the four forms and what they do
| Form | Who or what it enrolls | When you use it | Signed by |
|---|---|---|---|
| CMS-855I | An individual physician or non-physician practitioner | First Medicare enrollment of the person; changes to the person's information; revalidation | The practitioner |
| CMS-855B | A clinic or group practice (the organization and its tax ID) | Forming a new group; adding a practice location; changing ownership, banking or managing staff; revalidation | An authorized or delegated official of the group |
| CMS-855R | The reassignment of the individual's Medicare benefits to the group | When a practitioner joins a group, or leaves one | Both the practitioner and the group official |
| CMS-855O | A physician who only orders, certifies or refers, and does not bill | Rarely in practices; used for residents, some hospitalists and others who never bill Medicare directly | The practitioner |
The 855I is personal to the clinician. It carries their NPI, licenses, specialty, education, practice locations and, critically, their answers to the adverse legal history questions. Once a physician has an 855I on file, it travels with them; a physician who moves from one group to another does not file a new 855I but updates the existing record and files a new 855R with the new group.
The 855B belongs to the organization. It carries the group's legal business name exactly as the IRS knows it, the tax identification number, the practice locations, the owners and managing employees, and the bank account (through the companion CMS-588 electronic funds transfer form). A group files one 855B when it forms and then updates it for every change. Most practices never file a second full 855B; they file changes of information.
The 855R is the piece people forget. Medicare pays the person who furnished the service unless that person has reassigned the right to payment to an organization. The 855R is that reassignment. Without it, the group's claims for the new physician deny with CO-B7 (provider not certified or eligible to be paid for this service on this date), even though both the physician and the group are enrolled.
The order to file when a physician joins
First, look the physician up in PECOS or ask them. If they have an active Medicare enrollment anywhere, they have an 855I record, and you skip to the reassignment. If they are new to Medicare, complete the 855I first; in PECOS, the reassignment is added as part of the same application.
Second, file the 855R linking the physician to your group, signed by the physician and by the group's authorized official. In PECOS this is one screen. On paper it is a separate form, and the MAC will not process it until the 855I has been approved.
Third, confirm the group's 855B is current. If the physician will work at a location not listed on the group's enrollment, add it. If the group's authorized official has changed since the last filing and nobody updated it, the MAC will reject the 855R signature, which is a common and maddening delay.
Medicare's effective date for a physician is the later of the date the application was filed or the date services began at the new location, and the MAC allows retrospective billing for up to 30 days before the effective date in most cases (90 days in a declared disaster). This is why filing before the start date matters and why the orthopedic group above lost three months. Our credentialing and enrollment team files the 855R the day the offer letter is signed, even when the start date is months away.
What gets applications rejected or returned
The single largest cause is a mismatch between what the form says and what another government record says. The legal business name on the 855B must match the IRS CP-575 letter or a current IRS document character for character. The practitioner's name on the 855I must match the NPPES record for the NPI. The practice address must be a physical location, not a P.O. box. When these disagree, the MAC sends a development request, the clock stops, and if nobody answers within 30 days the application is rejected and you start over.
The second cause is the signature. Paper forms need original or acceptable electronic signatures from the right person, dated. An 855R signed by the office manager is returned. In PECOS, the e-signature must be completed by the practitioner and the official from their own accounts, and applications sit for weeks because one of them didn't log in to sign.
The third cause is incomplete adverse legal history. Section 3 of the 855I asks about convictions, exclusions, license actions and more. A physician who had a license reprimand ten years ago and answers "no" has made a false statement on a federal form. A physician who answers "yes" and attaches the documentation usually enrolls without incident. Coach physicians to answer completely and to bring the paperwork.
Keeping the enrollment alive
Medicare requires revalidation of every enrollment record every five years (every three for DMEPOS suppliers). The MAC sends a notice about six months before the due date to the correspondence address in PECOS, and the due date is also visible in the Medicare revalidation lookup tool. If the practice misses it, the enrollment is deactivated, claims stop paying, and reactivation requires a full application with a new effective date and, often, a gap in payment that is not recoverable.
Changes of information must be reported within 30 days for changes of ownership, practice location and adverse legal actions, and within 90 days for everything else. Bank account changes are the ones that hurt when missed: a group that moves banks and forgets the CMS-588 will have Medicare deposits bounce, and the MAC will suspend payment until the record is fixed.
When a physician leaves, file the 855R to terminate the reassignment as of the last day. If you don't, the departed physician remains linked to your group, and if they bill elsewhere under a new group, the MAC may question the overlap. It also leaves your group responsible for the physician's records on revalidation.
Questions we hear
Does a nurse practitioner or physician assistant use the same forms?
Yes. Non-physician practitioners enroll on the 855I and reassign with the 855R exactly like physicians. The specialty code and the supervision or collaboration information differ, but the forms and the order are the same.
Do we have to pay the Medicare application fee?
Physician and non-physician practitioner enrollments, and physician group practices, are not subject to the application fee. The fee applies to institutional providers and certain suppliers. If your practice also enrolls as a DMEPOS supplier or an independent diagnostic testing facility, that enrollment does carry the fee, and the amount changes each year.
How long does it take?
Depends on the MAC and the season. In our experience a clean PECOS application with reassignment is processed in a few weeks to a couple of months; a paper application or one with a development request takes longer. Nobody can guarantee a date, which is why filing early is the only strategy that works.
What to do this week
- Log into PECOS and print the current enrollment record for the group and every practitioner; confirm names, addresses, officials and bank information.
- Check the revalidation due date for each record in the Medicare revalidation lookup tool and put the dates on the credentialing calendar.
- Compare the group's legal business name on the 855B record against the IRS letter.
- For any practitioner who left, confirm the reassignment was terminated.
- Write a one-page checklist for the next new hire: 855I status, 855R filing, location check, effective date.
