Enrolling a new practice in Medicare through PECOS. The day you file sets the first day Medicare can pay.

A new practice enrolls in Medicare through PECOS, CMS's online enrollment system. The practice and each clinician need an NPI, and whoever files needs an Identity & Access login. The group files a CMS-855B, and each clinician files a CMS-855I that reassigns their Medicare payments to the group. The effective date is the later of the filing date and the first day of service at that location.^AD

Before PECOS: the NPI record and the login.

Every clinician has one individual NPI. A group has an organization NPI of its own, and a clinician who has incorporated holds both: one for themselves and one for the corporation or LLC. A sole proprietor uses the individual number.^B

An NPI is required for Medicare and does not enroll anyone. CMS says so plainly, and adds that changing an NPI record in NPPES does not change the Medicare enrollment.^B The two records are kept separately, and the contractor compares the application against both, so we make them agree before anything is filed.

PECOS, NPPES and a few other CMS systems share one login, the Identity & Access account. For a group, the person who registers as the Authorized Official sets up the organization there. That person, or an Access Manager they approve, can add staff and let an outside firm work on the practice's behalf as a surrogate.^C I&A passwords expire on a short, fixed cycle. An expired password locks the login and nothing else: the enrollment and the claims payments carry on.^C

Which forms a new practice files.

PECOS asks a series of questions at the start and picks the form from the answers. For a medical group, three forms matter.^AG

• The CMS-855B enrolls the practice itself as a clinic or group.
• The CMS-855I enrolls each physician or non-physician practitioner. CMS has merged the old reassignment form, the CMS-855R, into it, so the same application now sends that clinician's payments to the group.
• The CMS-855O is for a clinician who only orders or certifies, such as tests or equipment, and never bills Medicare.

Physicians, non-physician practitioners and their organizations pay no Medicare application fee. Institutional providers and equipment suppliers pay it, so a practice that also supplies durable medical equipment files a separate, fee-bearing enrollment for that.^A

Who signs, and what holds a file back.

Only the Authorized Official can sign the practice's first application. After approval, an Access Manager can sign changes, updates and revalidations. Each clinician signs their own CMS-855I.^A

The Medicare Administrative Contractor for your region reviews the file. It will not fully process a PECOS application until three things are in: the signatures, the fee where one applies, and the supporting documents, all of which can be uploaded in PECOS.^A When the contractor needs more, it sends a request with a deadline. Miss it and the contractor may reject the application, which means starting again with a new filing date.^A

What sets the timing.

For physicians, practitioners and their groups, federal rule sets the effective date as the later of two dates: the day the application that was later approved was filed, and the day the clinician first saw patients at the new location.^D Nothing else moves it earlier. A clinician who starts seeing patients before the file goes in may have visits Medicare never pays for.

There is a narrow exception. If circumstances kept a clinician from enrolling in advance, and every program requirement was already met, Medicare allows retrospective billing for a fixed window before the effective date, set in 42 CFR 424.521, at the enrolled location only.^E We treat that as a safety net, never a plan.

The contractor's pace depends on how clean the file is and how fast each request is answered. PECOS files tend to move faster than paper, CMS notes.^G

What trips new practices up.

• The address or name in NPPES differs from the application. The contractor asks, and the file waits.
• The person doing the work is not the Authorized Official in I&A and has no surrogate access, so nobody on hand can sign or submit.
• A clinician enrolls without reassigning to the group, and the group has no way to bill for their visits.
• A request from the contractor sits in an inbox nobody watches until the deadline passes.
• A change goes unreported. A new owner, a new Authorized Official or a new practice location has a shorter reporting window than other changes, and the clock starts the day the change happens.^A

After approval: keeping the enrollment alive.

Changes go through PECOS, the same way the application did. Every enrollment also has to be revalidated on a cycle CMS sets. CMS posts upcoming due dates on its public Medicare Revalidation List, and the contractor sends a notice ahead of the date. A revalidation sent too early without a notice is returned. A missed one can put a hold on Medicare payments or end the practice's billing privileges, and getting them back takes a complete new application.^F Our note on Medicare revalidation covers the cycle in detail.

We run the whole file: the NPPES check, the I&A setup and surrogate access, each form, every contractor request and the approval. The practice's application is $350, and each clinician's is $250. Once Medicare approves, claims go out under the effective date, and if we run your billing we follow each one to payment.

Short answers.