Enrolling a New Clinician in Medicare: PECOS, 855I and Reassignment

Start with a bright line: a clinician who will treat Medicare beneficiaries in their own right, rather than as staff billed incident to a supervising practitioner, must either be enrolled in Medicare or have a valid opt-out on file.

Medicare law — section 1848(g)(4)(A) of the Social Security Act, as CMS's provider enrollment FAQ for MFTs and mental health counselors summarizes it — requires physicians and non-physician practitioners to submit claims for all their Medicare patients, and both submitting claims and being paid require enrollment.

That obligation does not borrow from anything else the clinician is enrolled in.

Enrolling in Medicaid does not enroll a clinician in Medicare; a hire who will see Medicare patients enrolls in Medicare separately, on its own application and its own clock.

Two things belong to the hire, not to you.

They bring their own NPI — a practitioner may hold only one Type 1 (individual) NPI and uses that same NPI for Medicare and Medicaid enrollment — and their billing identity stays theirs: a provider may not sell its Medicare billing number or let another individual or entity use it.

So the standard way to bill a new hire's sessions is their own enrollment, reassigned to the group.

Billing staff work under a supervising practitioner's number is a separate Medicare mechanism with its own conditions, covered in our incident-to billing guide.

Your side of the file matters just as much: the group has to be in Medicare too.

To establish a reassignment, both the individual practitioner and the group must be currently enrolled or concurrently enrolling — the group enrolls through PECOS or the paper CMS-855B.

An owner-clinician can sit on both sides at once: CMS describes an MFT or MHC enrolled as an individual practitioner who is also an owner of the group — the practitioner files the CMS-855I, while the group files the CMS-855B.

The ordering-and-referring wrinkle

A clinician who never bills Medicare can still need to be in it.

For the practice to be paid for ordered imaging, clinical lab services or DMEPOS, the claim must carry the NPI of the ordering physician or eligible professional, who must be enrolled in Medicare in an approved status or have validly opted out.

If your psychiatrist or psychiatric nurse practitioner orders labs, that requirement reaches them; for a hire who only orders and refers without billing, CMS's Program Integrity Manual lists the CMS-855O as the enrollment route.

Enrollment is one workstream in the ramp that follows a signed offer.

The role-by-role guides on our behavioral health hiring hub cover the rest, from screening to pay.

The clinician's individual application runs through PECOS, CMS's online enrollment system, or the paper CMS-855I.

If you have run into older guidance naming a separate CMS-855R reassignment form, discard it: CMS's Medicare Program Integrity Manual states that the 855R has been discontinued, and the CMS-855I now captures the reassignment information it used to collect.

One signature rule shapes the whole workflow: the enrolling or enrolled practitioner is the only person who can sign the PECOS application or the paper CMS-855I, and a practitioner may not delegate that authority to anyone else.

Your staff or a credentialing vendor can prepare the file, but the clinician signs it.

What staff can do is serve as the application's contact person — a practice can name office or credentialing staff, and the Medicare Administrative Contractor (MAC) will discuss only the pending application with that contact.

Where the clinician sits on the form depends on the credential.

CMS's enrollment FAQ directs MFTs, mental health counselors and counselors licensed under another title to select the Undefined Non-Physician Practitioner Specialty option in section 2H of the paper CMS-855I and write in MFT or MHC, while PECOS lists the MFT and MHC specialties directly.

The FAQ said a later paper-form update would add the specialties, so confirm the current 855I edition with your MAC before filing on paper.

What the application puts a hire through also depends on the credential.

CMS places MFTs and MHCs in the limited screening risk category, which involves license verification and a range of database checks, and MFTs and MHCs are not required to pay a Medicare enrollment application fee.

After filing, watch the correspondence.

When a MAC needs more information it sends a development letter, and the provider has 30 calendar days to respond — no response, and the application is rejected.

Route enrollment mail to an inbox someone actually monitors, because a development letter that sits unread burns the clock.

Approval produces two identifiers, and they do different jobs: the NPI is what goes on claims, while the PTAN authenticates the provider when using MAC self-help tools.

A practitioner who enrolls in Medicare in more than one state receives a separate PTAN for each state.

Reassignment is the piece that makes the hire payable to you instead of to them: it lets your organization submit claims and receive payment for the Medicare Part B services the clinician furnishes as a member of the group.

The enrollment is the clinician's; the reassignment is what routes the payment to the practice.

Medicare bars reassignment of benefits except in the specific situations its rules name, and employment is one of them: Medicare may pay a practitioner's employer when the practitioner is required, as a condition of employment, to turn over the fees for their services to the employer.

The rules name contractual arrangements as another exception — the route for a clinician who contracts with the group rather than one you employ.

Mechanically, the reassignment is reported on the clinician's own application.

On the paper CMS-855I, the reassignment information goes in section 4F, the practitioner signs section 15B, and your group's Authorized or Delegated Official signs section 15C.

Both parties being enrolled or concurrently enrolling, covered above, is the precondition.

Three terms of the arrangement are worth knowing before you sign the employment agreement:

• Contractors carry shared liability. Where a group bills for a contracted practitioner's services under a contractual reassignment, the group and the practitioner are jointly and severally responsible for any Medicare overpayment — the rule states that responsibility for the contractual exception.
• The hire can see the claims. A practitioner who reassigns benefits has unrestricted access to the claims the group submits for their services, whether they are an employee or a contractor.
• No separate bank setup. A practitioner who reassigns all Medicare benefits to the group does not need to submit their own EFT agreement.

If the group is already enrolled — billing for clinical social workers, say — adding MFTs or mental health counselors does not change the group's PTAN.

The MAC issues each newly enrolled MFT or MHC an individual PTAN that links them to your group.

Reassignment covers the hire's own professional services as a group member.

Staffing that includes associates and technicians delivering care under a supervisor raises a different billing question, which our incident-to billing guide takes up.

Billing privileges do not start when the offer is signed.

For physicians and non-physician practitioners, the effective date of Medicare billing privileges is the later of the date an application that is later approved was filed, or the date services began at a new practice location.

Filing early is what protects the start date you and the hire agreed on.

When a hire inevitably begins seeing clients before approval lands, Medicare allows limited retroactive billing.

Physicians and non-physician practitioners who met all program requirements — including state licensure — may bill retrospectively for up to 30 days before their effective date if circumstances precluded enrolling in advance, and the services must have been furnished at the enrolled practice location.

Ninety days is the disaster case, not the default: the regulation extends retroactive billing to 90 days only where a Presidentially-declared disaster prevented enrollment in advance.

Build the schedule on the 30-day window and the filing-date rule, and treat any plan that assumes more as a plan built on the wrong number.

How long approval itself takes is the other half of the scheduling question, and it belongs to the wider sequence — NPI, Medicare, CAQH, payer panels — rather than to this form alone.

We walk the whole credentialing timeline, including Medicare's processing standards, in that guide.

Schedule the first Medicare client around the effective-date rule, not around the approval date you are hoping for.

Enrollment is not the only posture a clinician can hold toward Medicare — opting out is the other, and it changes what your practice can do with the hire.

Clinical social workers, marriage and family therapists and mental health counselors are among the practitioners who may opt out of Medicare.

Opting out is a filing, not a preference: the practitioner must submit an opt-out affidavit to each Medicare Administrative Contractor with which they would otherwise file claims.

An opt-out runs in 2-year periods that renew automatically unless the practitioner properly cancels it — so an opt-out follows a hire in the door, and it does not quietly lapse on its own.

For the employer, the limit is absolute.

An opted-out practitioner's affidavit acknowledges they may receive no direct or indirect Medicare payment for privately contracted services, whether as an individual, an employee of an organization, or under a reassignment of benefits — and no Medicare payment may be made to any entity for their services.

A group therefore cannot bill Medicare for an opted-out hire: the reassignment route this guide describes runs through an enrolled clinician, and a valid opt-out forecloses it.

So ask about opt-out status during hiring, not after.

A candidate with an active opt-out can still be a strong hire — but the practice is hiring them for non-Medicare work, and the start date for any Medicare caseload waits on the opt-out's rules, not on an enrollment application.

Enrollment is a standing obligation, not a one-time gate.

Medicare providers must revalidate their enrollment — resubmit and recertify the accuracy of the enrollment information — every 5 years, and submit the revalidation within 60 calendar days of CMS's notice; CMS may also require a revalidation off the normal cycle.

The notice is not a surprise.

CMS posts revalidation due dates seven months in advance on its Revalidation List, and the MAC sends a notice about three to four months before the due date.

Miss it anyway and the consequences land on your revenue: failing to revalidate on time can mean a hold on Medicare reimbursement or deactivation of billing privileges.

Between revalidations, the enrollment's certification is where exclusion screening hooks in: to keep Medicare enrollment active, a provider certifies it does not employ or contract with individuals or entities excluded from federal health care programs.

The rule sets no checking frequency, so set a schedule your practice owns — our exclusion screening guide covers the checks.

The enrollment also carries reporting clocks of its own.

Within 30 days, report a change of ownership, any adverse legal action, or a change, addition or deletion of a practice location.

All other enrollment changes are reported within 90 days.

Staff departures sit squarely in this system.

When a clinician leaves, the reassignment is terminated on the CMS-855I, and the payment clock is unforgiving: Medicare stops paying the group for that clinician's services the day after the termination effective date.

Filing the termination is departure paperwork, not optional cleanup — it is what stops claims going out under a reassignment that has already ended.