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Credentialing & Enrollment

Medicare Provider Enrollment: PECOS, CMS-855 Forms and Your PTAN, Step by Step

Who files which form, in what order, how long CMS gives the contractor, what you can bill before approval, and how Railroad Medicare piggybacks on Part B.

Medicare provider enrollment is the process of applying to Medicare for billing privileges: you get an NPI, file the right CMS-855 application in PECOS (or on paper), your Medicare Administrative Contractor (MAC) reviews it, and you receive a PTAN and an effective date from which you can bill Medicare. Physicians, non-physician practitioners and their groups pay no Medicare application fee.

If you want to know what PECOS itself is, how I&A access and surrogacy work, or how it compares with NPPES and CAQH, read what PECOS is first. This page is the filing sequence.

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Updated 2026-10-23. Reviewed by Jacob Greenberg, ClaimCarePro.

Medicare enrollment for providers, at a glance

The order matters: a group that does not exist in PECOS yet cannot receive a reassignment.

Medicare provider enrollment steps in order
StepWhat happensWhere
1. NPIGet an individual (Type 1) NPI in NPPES; groups also need an organizational (Type 2) NPI.NPPES
2. I&A accessCreate an Identity & Access login. Groups name an Authorized Official, who approves anyone else (including an outside enrollment company as surrogate).I&A / PECOS
3. Group enrollmentA new group files its own CMS-855B, plus the CMS-588 and the CMS-460 if it will participate.PECOS
4. Individual enrollmentEach practitioner files a CMS-855I, with section 4F reassigning benefits to the group where one exists.PECOS
5. SignaturesThe practitioner and the group’s authorized or delegated official e-sign; a surrogate cannot sign for them.PECOS e-signature
6. MAC reviewThe MAC verifies, may send a development request (answer within 30 days), and may order a site visit.Your MAC
7. ApprovalApproval letter with PTAN and effective date; then EDI and portal enrollment with the MAC.Your MAC
8. Railroad MedicareRequest a separate Railroad PTAN from Palmetto GBA once Part B is active.Palmetto GBA

Who enrolls: individual, group or reassignment?

Every physician or practitioner who bills Medicare needs an individual enrollment, but who gets paid depends on how you practice:

  • Solo, billing under your own number: one CMS-855I, plus the CMS-588 in your own name and, if you participate, your own CMS-460.
  • New group: the group files a CMS-855B, CMS-588 and CMS-460 first; then each practitioner files a CMS-855I reassigning benefits to it.
  • Joining an existing group: a CMS-855I with section 4F reassignment (the old CMS-855R is discontinued, per CMS's consolidated 855I bulletin). If you are already enrolled elsewhere, it is a reassignment and a practice-location update, not a new enrollment.
  • Ordering or referring only: the CMS-855O, which lets you order and certify but not bill.

Which NPI goes on which line trips up more applications than any form choice; our page on NPI Type 1 vs Type 2 covers it.

How to enroll as a Medicare provider, step by step

  1. Get your NPI in NPPES and make sure the name, address and taxonomy match your state license. CMS's PECOS fact sheet warns that updating NPPES does not update your Medicare record.
  2. Set up I&A access. For a group, the Authorized Official registers and approves everyone else. An enrollment company works your record as an approved surrogate; no one should hand over a password.
  3. Collect the documents before you open PECOS: license, IRS letter for the group's legal name and tax ID, a voided check or bank letter in the legal business name, practice locations, ownership and managing-employee details. Our credentialing intake checklist is the full list.
  4. File in PECOS at pecos.cms.hhs.gov. Its scenario questions decide which sections you complete. CMS's enrollment guide allows paper only if you cannot apply online, and First Coast also accepts uploaded paper forms through its Provider Enrollment Gateway.
  5. Get it signed. PECOS emails the practitioner and the group's official a signature request. Nothing moves until they sign.
  6. Answer the MAC within 30 days. A development letter starts a 30-day window from the date on the letter (First Coast roadmap).
  7. Read the approval letter. It carries your PTAN and effective date. Check the effective date against your first date of service the day it arrives.
  8. Finish the plumbing: EDI enrollment and portal access with your MAC, then the Railroad Medicare PTAN (below).

Medicare provider enrollment forms

Every PECOS application is one of these forms, filled in online.

Medicare enrollment forms, who files each, and what each covers
FormWho files itWhat it covers
CMS-855IIndividual physicians and non-physician practitioners, including sole proprietorsIndividual enrollment; reassignment to a group in section 4F (the old CMS-855R is discontinued)
CMS-855BGroups, clinics and other Part B suppliers (not DMEPOS)The organization’s enrollment, ownership, managing employees and practice locations
CMS-855OPhysicians and eligible practitioners who only order, certify or referEnrollment to order and certify; cannot bill Medicare
CMS-588The payee: the group, or the solo practitioner billing under their own numberElectronic funds transfer; required at initial enrollment, revalidation and certain changes
CMS-460The billing entity that elects to participate (for a group, the group)Participating physician or supplier agreement; accept assignment on all covered services
CMS-855A / 855SInstitutional providers / DMEPOS suppliersSeparate tracks, not covered on this page

Source: CMS's Medicare Provider Enrollment booklet (MLN9658742). On the CMS-460: you have 90 days after the initial approval letter to decide whether to participate, and after that you can change only during the annual open enrollment period, generally mid-November through December 31. Practitioners who reassign all their benefits to a participating group inherit its status and should not be marked participating on their own (CMS Program Integrity Manual, ch. 10, §10.6.11).

PTAN vs NPI: which number is which?

Your NPI identifies you to every payer; your PTAN identifies one Medicare enrollment. CMS's manual defines it plainly: for Part B suppliers, “the Medicare identification number is the Provider Transaction Access Number (PTAN).” The MAC issues it on approval. Claims still go out under the NPI, but the PTAN is what you use to sign up for EDI, and log in to the MAC portal.

One provider, one individual NPI, but possibly several PTANs: one for each group they reassign to, sometimes one per practice location, and a separate one for Railroad Medicare. When a practitioner tells us “I already have Medicare,” the useful question is which PTAN, at which group, at which address.

How long does it take to get Medicare enrollment approved?

CMS’s own processing standards for MACs, not a promise for any one application.

CMS contractor processing standards for initial and change-of-information applications
Application typeStandardOuter limit
PECOS, no site visit, development or fingerprinting95% within 15 calendar days100% within 50 calendar days
PECOS, with site visit, development and/or fingerprinting95% within 50 calendar days100% within 85 calendar days
Paper, no site visit, development or fingerprinting95% within 30 calendar days100% within 65 calendar days
Paper, with site visit, development and/or fingerprinting95% within 65 calendar days100% within 100 calendar days

Source: CMS Program Integrity Manual, chapter 10, §10.5 (Rev. 13717, issued July 8, 2026). The clock is the contractor's from receipt, and a development letter moves an application into the slower row. That is why the “60 to 90 days” figure repeated online is less useful than the question of whether your application will need development at all. Two waits sit outside these numbers: the days before a practitioner signs, and, for paper sent through First Coast, the two weeks First Coast says to allow for an application to be uploaded into its system.

Effective date and retroactive billing: what you can bill, from when

Your Medicare effective date is the later of two dates: the day you filed the application the MAC approved, or the day you first furnished services at that practice location (42 CFR 424.520(d)). From there you may bill retrospectively for up to 30 days before the effective date if circumstances prevented enrolling earlier, or 90 days after a Presidentially declared disaster, provided you already met every requirement, state licensure included (42 CFR 424.521(a)).

So yes, you can retroactively bill Medicare after enrollment is complete, but the window is anchored to when you filed, not when you were approved. A physician who starts seeing patients on the 1st and files on the 20th is covered. One who files six weeks after starting has visits no window reaches. Once approved, those claims still have to go out inside Medicare's one-year timely filing limit (42 CFR 424.44). Holding claims while the application is pending is normal; filing late is the mistake that cannot be fixed. Recurring dates after approval are on recredentialing and credentialing maintenance.

Railroad Medicare provider enrollment (Palmetto GBA)

A separate PTAN, but not a separate application.

Railroad Medicare provider enrollment is a request for a second PTAN, made after your regular Part B enrollment is active. Patients covered through the Railroad Retirement Board are processed by Palmetto GBA, a different jurisdiction from your local MAC, so their Part B claims need a Railroad Medicare PTAN. According to Palmetto's Enroll in Railroad Medicare page (published January 13, 2026):

  • You must be enrolled in Medicare Part B with your local MAC first.
  • You do not file another CMS-855. Palmetto verifies the enrollment on file with your MAC and creates a matching Railroad Medicare file.
  • Request the PTAN with Palmetto's PTAN Lookup and Request Tool when you are ready to submit a claim; paper claim submitters can start the request with a CMS-1500.
  • Allow up to 30 days. The Railroad PTAN's effective date is retroactive to your Part B PTAN's effective date, and Palmetto mails a confirmation letter.
  • Then enroll for electronic claims (EDI) with Palmetto separately.

The practical trap: a practice sees its first railroad retiree months after Part B approval, the claim rejects, and nobody connects it to a missing PTAN. Requesting it at the same time as EDI setup costs nothing.

Medicare credentialing: what the term means

“Medicare credentialing” and “credentialing with Medicare” almost always mean the enrollment on this page. Traditional Medicare does not run a commercial-style credentialing committee or read CAQH; the MAC verifies your license, identity and eligibility as part of enrollment, and that is the whole approval.

Medicare Advantage is different. Advantage plans are private health plans that must run their own credentialing and recredentialing (42 CFR 422.204), so each one you want to join is its own application, usually reading your CAQH profile. How credentialing, enrollment and contracting differ is on what provider credentialing is, and the commercial payers, plan by plan, are in our payer credentialing guides.

Why Medicare applications stall

In our casework the cause is usually bad data from the providers, not the contractor.

Common causes of delayed or returned Medicare enrollment applications
ProblemWhat it looks like
Address mismatchThe practice location in PECOS reads differently from NPPES, the state license or the W-9: an old suite, a moved office, a mailing address entered as a practice location.
Legal name or TIN mismatchThe legal business name or tax ID on the 855B differs from the IRS record (CP-575 or 147C letter) or from NPPES.
Wrong NPI in the wrong placeThe group’s Type 2 NPI on an individual line, or the practitioner’s Type 1 where the group belongs.
Bank account in the wrong nameThe CMS-588 account is personal, or only in a DBA name, instead of the legal business name.
Stale or missing signatureThe practitioner never opened the e-signature email, or the signature is dated too long before the MAC receives it.
Development letter missedA request for information arrives, nobody answers inside the 30-day window, and the application is rejected rather than held.
Abandoned draftA half-built PECOS application waits on a document and is cleared out as inactive.
Par status entered twiceA practitioner reassigning to a participating group is also marked participating individually, which the MAC has to unwind.

Every row is the application disagreeing with another record. Before we file, we check the application line by line against NPPES, the state license, the IRS letter and the bank letter. After filing, we follow up weekly and log every contact with the date, the representative and the reference number, so a development letter never sits unanswered.

After approval: the dates that keep running

  • Revalidation generally every five years, every three for DMEPOS suppliers, or off-cycle when CMS asks (42 CFR 424.515; CMS revalidation).
  • Change reporting: changes of ownership or control, practice location and final adverse legal actions within 30 days; other changes within 90 (MLN9658742).
  • Deactivation can follow a missed revalidation, an unreported change, or no Medicare claims for six consecutive months (42 CFR 424.540).

What we charge to handle Medicare enrollment

ClaimCarePro files Medicare enrollment for a flat $250 per payer application, per provider, with weekly follow-up until the approval letter arrives. Re-credentialing and revalidation are $250 when due, and maintenance is $99 per provider per year. A new practice can take the new-practice bundle at $1,750 per provider ($1,400 for each additional provider on the same group and payers); CAQH setup for the commercial and Advantage plans is $250. Everything is on credentialing services.

Medicare provider enrollment questions, answered

How do I enroll as a Medicare provider?
Get an individual NPI in NPPES, set up an Identity & Access (I&A) login, then file the CMS-855 application that fits you in PECOS (the CMS-855I for an individual physician or practitioner, the CMS-855B for a group), with the CMS-588 for electronic payments. Your Medicare Administrative Contractor reviews it, may ask for more information, and sends an approval letter with your PTAN and effective date.
What is PECOS enrollment?
PECOS enrollment is filing your Medicare enrollment application online in PECOS, CMS’s Provider Enrollment, Chain, and Ownership System, instead of on a paper CMS-855. CMS calls it the preferred method, and its manual holds contractors to a faster processing standard for PECOS applications than for paper ones.
How long does it take to get Medicare enrollment approved?
CMS does not promise a date, but it sets standards for its contractors. For a PECOS application that needs no site visit, development request or fingerprinting, the MAC is to process 95 percent within 15 calendar days and all of them within 50. With a development request or site visit, the standard is 95 percent within 50 days and all within 85. Paper takes longer: 30 and 65 days, or 65 and 100.
Can you retroactively bill Medicare after enrollment is complete?
Yes, within limits. Your effective date is the later of the date you filed the application that was approved or the date you started seeing patients at that location, and you may bill for services up to 30 days before that effective date if circumstances kept you from enrolling earlier (90 days after a Presidentially declared disaster). Services more than 30 days before your filing date cannot be billed.
What is the difference between a PTAN and an NPI?
Your NPI is the national identifier every payer uses, issued by NPPES. Your PTAN (Provider Transaction Access Number) is the Medicare-only number your MAC assigns when it approves your enrollment, and you need it for Medicare portals and EDI enrollment. A provider has one individual NPI but can have several PTANs, one per group or location enrollment.
How do I enroll with Railroad Medicare?
Enroll with your local Part B MAC first. Then request a Railroad Medicare PTAN from Palmetto GBA with its online PTAN Lookup and Request Tool. No separate CMS-855 is filed: Palmetto copies your Part B enrollment, makes the Railroad PTAN effective on the same date as your Part B PTAN, and asks you to allow up to 30 days.
Is the CMS-855R still used for reassignment?
No. CMS merged the CMS-855R into the CMS-855I, and reassignment of benefits to a group is now section 4F of the CMS-855I (groups can also add reassignments on the CMS-855B). MACs return reassignment applications filed on the old 855R version.
Who files the CMS-460 participation agreement?
The billing entity. For a group, that is the group: practitioners who reassign all their benefits to a participating group take on the group’s participation status and should not be marked participating on their own. A solo practitioner billing under their own number files their own. CMS gives you 90 days after the initial approval letter to decide.
Is Medicare credentialing the same as Medicare Advantage credentialing?
No. Traditional Medicare enrolls you through PECOS and your MAC; it does not run a commercial-style credentialing committee or use CAQH. Medicare Advantage plans are private health plans that run their own credentialing under 42 CFR 422.204, so each Advantage plan you want to join needs its own application, often through CAQH.
How often does Medicare enrollment have to be revalidated?
Generally every five years, and every three years for DMEPOS suppliers, or whenever CMS asks off-cycle. CMS posts due dates in advance and your MAC sends a notice, and a missed revalidation can lead to held payments or deactivation of billing privileges.

Sources

Primary sources, read October 23, 2026.

Hand us the Medicare file

$250 per payer application, per provider. Medicare, Railroad Medicare, Medicaid and the commercial plans on one intake, followed up weekly.

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Updated 2026-10-23. Reviewed by Jacob Greenberg, ClaimCarePro.