What Is PECOS? Medicare Enrollment, Explained by the People Who File It
What the system does, how it relates to the CMS-855 forms, NPPES and CAQH, and the data problems that hold applications up.
PECOS (the Provider Enrollment, Chain, and Ownership System) is Medicare’s online enrollment system: the place where physicians, practitioners, groups and suppliers enroll in Medicare, report changes, reassign their benefits to a group and revalidate. CMS runs it at pecos.cms.hhs.gov, and your regional Medicare Administrative Contractor (MAC) reviews everything filed there. It holds your Medicare record only. It does not issue your NPI, and it is not the profile commercial insurers read.
This guide is written from the filing side: we handle provider enrollment nationwide, with clients live today in Florida and Kentucky.
Last updated October 16, 2026. Reviewed by Jacob Greenberg, ClaimCarePro.
What is PECOS for Medicare?
The enrollment record behind every Medicare claim you send.
CMS says a provider will not receive payment from Medicare until it is properly enrolled. PECOS is where that enrollment lives. According to the CMS PECOS fact sheet, you use it to enroll, revalidate an existing enrollment, update information and track application status. The PECOS provider page adds the piece that matters most to group practices: it is also where a clinician reassigns the right to be paid to an organization.
PECOS is the preferred route, not the only one: if you cannot apply online, CMS says you can use a paper application form.
What does PECOS mean? The forms behind the screens
Every PECOS application is a CMS-855 form, filled in online.
| Form | Who files it | What it covers |
|---|---|---|
| CMS-855I | Individual physicians and non-physician practitioners | Individual enrollment, and since the 2023 revision, reassignment of benefits too. CMS merged the old CMS-855R into it; MACs return 855R applications on the old version received after November 1, 2023 (CMS bulletin). |
| CMS-855B | Groups, clinics and other Part B suppliers | The organization’s own enrollment, ownership and practice locations. CMS says reassignment fields will be added to it in a future update. |
| CMS-855A | Institutional providers (hospitals, home health agencies, SNFs) | Part A enrollment for facilities. |
| CMS-855O | Practitioners who only order, certify or refer | Enrollment solely to order and certify, without billing Medicare yourself. |
I&A, surrogates and who can actually log in
Access is set up before anything gets filed.
You sign in to PECOS with an Identity & Access (I&A) account, the same login used for NPPES. Per the CMS I&A FAQ, an organization’s Authorized Official is its legal signatory and can approve Access Managers, who in turn manage staff users and surrogacy requests. A surrogate is an outside organization, such as a billing or enrollment company, that a provider has connected to so it can work the provider’s records.
The detail most guides miss: access is not signature authority. A surrogate can prepare the application, but the practitioner, or the group’s authorized or delegated official, still signs it. Setting up that connection is our step one; the provider never hands us a password. The rest of the intake list is on what we need from you.
Reassignment: when the group gets paid for your work
The step that links a clinician’s Type 1 NPI to a group’s billing number.
A physician who joins a group still needs their own enrollment. They enroll as an individual and reassign their benefits to the group, which then bills under its own number. Since 2023 both happen on the CMS-855I.
One pattern we see with our own clients: physicians who round at hospitals and need their own Medicare and payer ID numbers, while the hospital group bills their professional claims. They are not negotiating contracts; they need a clean individual record and a reassignment that matches the group’s. If you are deciding which NPI goes where on that claim, read NPI Type 1 vs Type 2.
Revalidation, effective dates and the 30-day rule
The three dates that decide which visits you can bill.
| Date | What the rule says | Source |
|---|---|---|
| Effective date | For physicians, practitioners and their organizations: the later of the date an application that was later approved was filed, or the date you first furnished services at the new location. | 42 CFR 424.520(d) |
| Retrospective billing | Up to 30 days before the effective date, if circumstances prevented enrolling in advance (90 days after a Presidentially declared disaster). You must already have met all program requirements, state licensure included. | 42 CFR 424.521(a) |
| Revalidation | Generally every five years; every three years for DMEPOS suppliers. CMS posts due dates seven months ahead and can request off-cycle revalidation. | CMS revalidations |
So the filing date matters more than the approval date: a provider who starts seeing Medicare patients and files six weeks later has a gap the 30-day window does not cover.
The ordering and referring check that denies other people’s claims
Your enrollment status affects the labs, imaging centers and DME suppliers you send patients to.
Medicare checks the ordering practitioner on claims for durable medical equipment, clinical laboratory services, imaging and home health. To pass, CMS says the orderer needs an individual (Type 1) NPI, an eligible specialty and a Medicare record in approved or opt-out status (CMS ordering & certifying). Organizational NPIs do not qualify.
The fix is not on the lab’s side: the ordering provider enrolls, fully or solely to order and certify on the CMS-855O.
PECOS vs NPPES vs CAQH
Three systems, three jobs, and none of them updates the others.
| PECOS | NPPES | CAQH (now DataSpring) | |
|---|---|---|---|
| Run by | CMS, reviewed by your MAC | CMS | DataSpring, which describes itself as formerly CAQH |
| What it holds | Medicare enrollment, ownership, reassignments, practice locations | Your NPI and the data behind it | A credentialing profile that participating commercial plans read |
| Who relies on it | Medicare only | Any payer or clearinghouse that looks up your NPI | Health plans that participate in it |
| Upkeep | Revalidation, generally every 5 years, plus change reporting | Report changes within 30 days | Re-attest every 120 days |
CMS’s fact sheet is blunt about the first two: an update to your NPI record in NPPES does not automatically update your Medicare enrollment, and the names must match between the two. The CAQH side is covered in what is CAQH.
What stalls a PECOS application
Where we see applications stall, the cause is data the provider can fix before filing.
Asked what holds enrollment applications up, Jacob Greenberg’s answer was short: “bad data from the providers.” Not slow contractors, not lost mail. The application says one thing and another record says something else:
- A practice address in PECOS that does not match NPPES or the state license, often an old suite number or a location that moved.
- A legal business name or TIN that differs from the IRS record, NPPES or the CAQH profile.
- A license or other document that lapsed between collecting it and filing.
Each one sends the application back for correction, so before we file we check the NPPES record, license, CAQH profile and application against one another, from the documents on our intake checklist. For the commercial side of the same process, see how to get credentialed with insurance companies, and for Florida payers specifically, the Florida credentialing guide.
PECOS questions, answered
What is PECOS for Medicare?
What does PECOS mean?
What is Medicare PECOS?
Do I have to use PECOS to enroll in Medicare?
Is PECOS the same as NPPES?
How often do I have to revalidate in PECOS?
Can I bill Medicare for patients I saw before my PECOS approval?
Why are claims denied when the ordering doctor is not in PECOS?
What does ClaimCarePro charge to handle Medicare enrollment?
Flat per-application pricing is on the pricing page. Unfamiliar term? Check the glossary.