PECOS and the 855 form family: 855I, 855B, 855R, 855O and 855A explained.
Five CMS-855 forms cover every way a person or organization can enroll in Medicare, and picking the wrong one — or filing one without the companion form it needs — is the single most common reason enrollment stalls before it even reaches a Medicare Administrative Contractor's review queue. This guide walks through each form, who actually files it, what it requires, and the account setup that has to exist before any of them can be submitted.
Key takeaways
- The form follows the entity, not the specialty. 855I is for individuals, 855B for groups, 855R for reassignment, 855O for non-billing ordering/referring practitioners, 855A for institutions.
- An I&A account and Authorized Official have to exist first. You cannot file an organizational enrollment without one, and setting it up mid-application is a common source of delay.
- Most physician hires need two forms, not one. An 855I alone enrolls the person; it takes an 855R alongside it to let the group actually bill for them.
- PECOS online beats paper on every metric that matters. Real-time validation catches missing fields before submission instead of weeks later.
Before you file anything: I&A access and the Authorized Official
Every 855 filing, online or paper, ultimately depends on someone having the legal authority to sign it, and PECOS enforces that through the CMS Identity and Access Management System at nppes.cms.hhs.gov/IAWeb. An individual practitioner filing their own 855I generally just needs their own I&A account tied to their NPI. An organization is different: it has to designate at least one Authorized Official in I&A — someone with the legal authority to bind the organization, such as an owner, chief executive, chief financial officer, or general partner — before an 855B, 855R, or most other organizational enrollment can be submitted on its behalf.
Practices routinely discover this requirement partway through building an application, not before, which forces a pause while the Authorized Official designation is created and, in some cases, verified against IRS or state business records. Setting up I&A access and confirming who holds the Authorized Official role is worth doing as the very first step of any enrollment project, not as a step you find out you're missing when the online application won't let you proceed. I&A also supports a Surrogate role, which lets an Authorized Official delegate day-to-day application work — data entry, document uploads, status checks — to office staff or a billing partner without handing over signing authority itself.
The five 855 forms at a glance
| Form | Who files it | What it does |
|---|---|---|
| 855I | Individual physicians and non-physician practitioners | Enrolls the individual and establishes their own Medicare billing number |
| 855B | Group practices, clinics, and other organizational suppliers | Enrolls the organization itself as a Medicare supplier |
| 855R | An enrolled individual, together with the receiving group | Reassigns the individual's right to receive Medicare payment to the group |
| 855O | Physicians and eligible practitioners who only order or refer | A lighter enrollment solely to order or refer Medicare-covered services, without billing Medicare directly |
| 855A | Institutional providers — hospitals, SNFs, home health agencies, hospices | Enrolls the facility itself, a substantially larger filing with its own survey and certification requirements |
855I: the individual practitioner
The 855I is the form nearly every physician, nurse practitioner, physician assistant, or other individual practitioner files to enroll in Medicare in their own right. It captures the practitioner's identity, education and training, professional licenses, board certifications, practice locations, and any final adverse legal actions that have to be disclosed. On its own, an approved 855I does one thing: it establishes that this individual is enrolled and eligible to bill Medicare directly, under their own name and NPI.
What it does not do is let a group bill and collect on that practitioner's behalf. That distinction surprises practices constantly, because an 855I can be fully approved — the physician shows as enrolled in PECOS — while claims submitted under the group's tax ID still deny, simply because the reassignment piece was never filed. If the physician is joining an existing practice rather than billing entirely independently, plan for the 855R from the start rather than treating it as an afterthought once the 855I clears.
855B: the group or organizational supplier
The 855B enrolls an organization — a group practice, clinic, ambulatory surgery center, or other organizational supplier — as its own Medicare entity, separate from any individual practitioner within it. It requires the organization's legal business name, tax identification number, every practice location the organization operates from, and detailed ownership and managing-control disclosures: who owns what percentage, who holds officer or director roles, and whether any owner or managing employee has a disclosable adverse legal history.
A brand-new practice entity files an 855B before it can receive any reassigned billing rights from its physicians, because there has to be an enrolled organization on the receiving end of an 855R. An existing group adding a new physical location also has to update its 855B to reflect that location — a step that gets missed constantly when the individual practitioner's paperwork gets all the attention and the group's own enrollment record quietly falls out of date.
855R: reassignment
The 855R is what actually connects an enrolled individual to an enrolled group for billing purposes. It names the practitioner, the receiving group, and every practice location where that reassignment applies, and both the individual (or their authorized delegate) and the group's Authorized Official have to sign it. PECOS online lets you build the 855I and 855R together in a single web submission when hiring a new physician into an existing group, which is generally the cleanest way to file, because the two applications process as one linked package rather than as two independent submissions that can drift out of sync.
Reassignment is location-specific, not a blanket authorization. A physician who splits time between two offices tied to different practice locations under the same group needs both locations reflected on the 855R; a physician who also sees patients at a second group with a different tax ID needs a separate 855R filed against that second group entirely. The mechanics of multi-location and multi-group reassignment, including what happens when a physician leaves and the reassignment has to be terminated, are covered in full in our reassignment and group enrollment guide.
855O: ordering and referring only
Not every physician who touches a Medicare claim bills Medicare directly. A physician who only orders lab work, imaging, durable medical equipment, or home health services, or who only refers patients to other Medicare providers, still has to be enrolled — using the lighter-weight 855O rather than a full 855I. This form skips most of the billing-specific detail a full enrollment requires (there's no practice location or reassignment component to build) but still requires an active NPI, valid state license, and PECOS or I&A identity verification.
This is the form residents need when they transition to attending status and start ordering tests independently, that locum tenens physicians frequently need when covering a practice without billing Medicare themselves, and that out-of-network specialists who refer patients into Medicare-covered services need even though they never submit a Medicare claim of their own. The full picture of who needs an 855O and how a missing one shows up as a downstream claim denial is in our ordering and referring provider guide.
855A: institutional providers
The 855A enrolls institutional providers — hospitals, skilled nursing facilities, home health agencies, hospices, comprehensive outpatient rehabilitation facilities, and similar facility-based entities. It is a materially larger filing than any of the practitioner-level forms: it captures ownership structure down to every disclosable interest, management and administrative arrangements, and it is typically paired with a state survey and certification process before Medicare will approve the enrollment, since these are provider types subject to Conditions of Participation rather than the lighter Conditions for Coverage that apply to most practitioner-level suppliers. Most physician practices will never touch an 855A directly, but it matters to understand it exists, because it is the form that has to be current and accurate for the facility a practice's physicians admit to or work within — and a facility with a lapsed 855A can create downstream billing problems for every practitioner enrolled at that location.
PECOS online versus paper submission
| Aspect | PECOS online | Paper CMS-855 |
|---|---|---|
| Field validation | Real-time; missing or inconsistent fields are flagged before submission | None; errors surface only when a contractor reviewer finds them |
| Tracking | Web tracking identifier issued immediately on submission | No equivalent until the contractor logs receipt, which can lag the mailing itself |
| Signature | Electronic signature by the Authorized Official or individual, within PECOS | Wet signature required, adding mail time in both directions |
| Linked applications | Multiple related forms (e.g. 855I + 855R) can be built and submitted as one package | Each form is a standalone mailed packet |
| Best for | The large majority of enrollments, revalidations, and changes | Situations where online access genuinely isn't available, or a specific contractor requires paper for an edge case |
There is essentially no scenario where paper submission is faster once I&A access is set up correctly. The one real advantage of paper is independence from PECOS system access entirely, which occasionally matters for an organization still working through I&A account issues, but that's a reason to fix the I&A access, not a reason to default to paper as a routine practice.
Confirm the I&A Authorized Official designation for your organization before you start recruiting, not after an offer is signed. It's a five-minute check when nothing is urgent and a multi-week bottleneck when a start date is already on the calendar.
Do and don't
- Confirm I&A access and the Authorized Official designation before starting any organizational filing.
- File the 855I and 855R together in one PECOS web session when hiring into an existing group.
- Use PECOS online by default; reserve paper for genuine access exceptions.
- Update the group's own 855B whenever a new practice location opens.
- Don't assume an approved 855I means the group can bill for that practitioner.
- Don't wait until an application is underway to discover nobody holds Authorized Official access.
- Don't treat a non-billing referring physician as exempt from enrollment entirely — that's what the 855O is for.
- Don't forget the 855A implications for the facilities your physicians work within, even if your practice never files one directly.
Want your 855 filings built and tracked correctly?
We confirm I&A access first, build linked 855I/855R submissions in PECOS, and chase every development request to the deadline.
Frequently asked questions
Do I need to file the 855I and 855R at the same time?
Not technically, but practically yes. The 855I enrolls the individual practitioner; on its own it does not let a group bill for that practitioner's services. If the goal is for the group to bill and collect on the physician's behalf, the 855R has to be filed as well, and most PECOS web submissions let you build both into a single online session so they process together rather than as two separate, sequential applications.
What is the I&A system and why do I need it before filing anything?
The CMS Identity and Access Management System, at nppes.cms.hhs.gov/IAWeb, is what grants a person the login and role needed to act in PECOS or NPPES on behalf of an individual or an organization. An organization has to designate an Authorized Official in I&A before anyone can file an 855B, 855R, or most other organizational enrollment on its behalf. Discovering mid-application that nobody holds this role is one of the most common and most avoidable delays in Medicare enrollment.
Is paper or online PECOS submission faster?
Online submission through PECOS is generally the faster and more reliable path because it performs real-time field validation, flags missing attachments before you can submit, and gives you a web tracking identifier immediately. Paper CMS-855 forms mailed to your Medicare Administrative Contractor still work, but errors surface only after a human reviewer finds them, which adds a full mail-and-review cycle before you even learn something was wrong.
Confirm before you rely on this. Payer contact details, portal URLs, required documents and credentialing timelines change without notice, and payers periodically rename, merge or migrate their systems. The process information on this page reflects standard industry practice as of August 2026 and is provided for general education — verify current requirements directly with the payer before submitting an application.