What are the three enrollment paths the ADA describes?

Participating provider, non-participating provider, and opt-out. A participating provider accepts Medicare's allowed amount as payment in full on every claim. A non-participating provider can still bill Medicare but may charge up to the limiting charge above the allowed amount on unassigned claims. An opted-out provider files an affidavit and leaves the Medicare billing system entirely for a 2-year term. The ADA publishes a separate step-by-step guide for each of the first two paths.

Does a dentist have to pick participating or non-participating before filing the 855I?

Yes. The 855I asks for this election directly, and it is not a formality: participating status is generally locked in for the calendar year once elected, with a limited annual open enrollment window to change it. Filing without deciding deliberately means defaulting into whichever box gets checked, which is not the same as choosing.

Does the specialty code actually change what gets paid?

It does not change the coverage rule at 42 CFR 411.15(i)(3), but it is the field Medicare Administrative Contractors and downstream reporting use to categorize the provider, and an oral surgeon or endodontist filing under the wrong or a generic code risks being processed against the wrong specialty-level edits. It is a data-accuracy step inside enrollment, not a payment-amount step, and treating it as cosmetic is how it gets skipped.

Where does PECOS fit into the ADA's steps?

PECOS is the system both the participating and non-participating ADA guides route the applicant through. Each guide is a screen-by-screen walkthrough of the same PECOS application, differing at the one screen where participation status and, since 2024, specialty code are elected. Paper filing (CMS-855I by mail) is still accepted but is the slower of the two paths CMS itself describes.

What happens if a dentist just wants to see the requirements before starting the application?

The ADA publishes a standalone document, 'Should I Enroll in Medicare?', built as a decision tree rather than a form walkthrough, meant to be read before opening PECOS. It is the document to start with, not the one to fill out.

How a Dentist Actually Enrolls in Medicare: The ADA's Own Steps, Form by Form.

Q: What is the specialty self-designation code on the 855I, and is it new?

It is a field on the 855I where a dentist selects a Medicare specialty code describing their practice type. CMS Transmittal R12231CP (CR 13323) added nine dental-specific codes, E3 through F5, covering dental anesthesiology, endodontics, oral pathology and radiology, oral medicine, orofacial pain, orthodontics, pediatric dentistry, periodontics, and prosthodontics, effective August 31, 2023 and implemented January 1, 2024. A dentist enrolling today selects from this list; a dentist who enrolled before 2024 was never asked and may still be carrying a generic designation.

The American Dental Association does not describe Medicare enrollment as a form. It describes it as a decision with three branches, participating, non-participating, or opt-out, and only after that decision does the actual paperwork begin. What it takes for a dentist to enroll in Medicare covers the forms themselves, CMS-855I and CMS-855B, and the opt-out affidavit’s 2-year term. This piece stays one level lower: the ADA’s own step sequence inside PECOS, and the one field on that sequence that changed in 2024 and that most practices enrolled before then have never touched.

What is the decision the ADA wants made first?

Before the ADA’s step-by-step guides open PECOS at all, its companion document, “Should I Enroll in Medicare?”, walks through three positions a dentist can occupy. A participating provider accepts Medicare’s allowed amount as payment in full on every claim, in exchange for a small fee-schedule advantage and inclusion in CMS’s public provider directories. A non-participating provider stays inside the billing system but can charge up to the Medicare limiting charge above the allowed amount on claims it does not accept assignment on, trading a lower guaranteed payment rate for more pricing flexibility per claim. An opted-out provider leaves the system for a 2-year term and can only see Medicare beneficiaries under private contract. The ADA treats this as the real decision. The forms that follow only implement it.

What does the participating-provider path actually look like?

The ADA’s step-by-step guide for participating providers walks the applicant through the PECOS screens in order: confirming the individual NPI is active, selecting the participating election, entering practice location and reassignment information if billing through a group’s Type 2 NPI, and submitting supporting identity and licensure documentation. The sequence is the same PECOS application referenced in the enrollment forms overview, screen by screen rather than form by form, and it ends at the same place, an application pending Medicare Administrative Contractor review.

What is different on the non-participating path?

The ADA’s non-participating guide is the same walkthrough with one screen changed: the participation election. Everything else, the NPI confirmation, the practice-location entry, the reassignment section for a dentist billing through a group, runs identically. The ADA publishes these as two separate documents rather than one document with a branch, which is itself a signal that CMS and the ADA both expect this to be a deliberate choice made once, not a checkbox glossed over on the way to the fields that feel more consequential.

What changed on the form itself in 2024?

CMS Transmittal R12231CP (CR 13323) added nine dental-specific specialty self-designation codes, E3 through F5, effective August 31, 2023 and implemented January 1, 2024.

The nine codes cover dental anesthesiology, endodontics, oral pathology and radiology, oral medicine, orofacial pain, orthodontics, pediatric dentistry, periodontics, and prosthodontics. A dentist completing the 855I today selects one of these on the specialty field, where before 2024 the form offered no dental-specific options at all. This does not touch the coverage question at 42 CFR 411.15(i)(3), a claim either qualifies under that regulation or it does not, regardless of the billing dentist’s specialty code. What it touches is how the Medicare Administrative Contractor’s systems categorize the provider afterward, and a specialty as consequential to claims processing as oral surgery, which accounts for the large majority of dentists who actually bill Part B, is now a field a new applicant is asked to get right rather than a field that used to not exist.

A dentist who enrolled before January 2024 was never presented with this choice. Nothing in the transmittal requires an existing enrollee to go back and update it, which means a practice’s enrollment record may still carry whatever generic designation was available at the time, unrelated to whether that dentist is, in practice, an oral surgeon, an endodontist, or a general dentist doing occasional qualifying work.

What should a practice check before assuming its enrollment is current?

Question	Where the answer lives
Participating or non-participating, and was it a deliberate choice?	PECOS enrollment record, or the original 855I submission
Was a specialty code selected, and does it match the dentist’s actual practice?	855I specialty field; codes E3-F5 added 2024-01-02
Is reassignment to the group’s 855B complete for every billing dentist?	PECOS reassignment section
Was the application filed through PECOS or on paper?	Confirms which ADA step-by-step guide applies

Where the how lives

Read the ADA’s own documents before opening PECOS, not after: “Should I Enroll in Medicare?” for the three-way decision, then the matching step-by-step guide, participating or non-participating, for the screen-by-screen walkthrough. What it takes for a dentist to enroll in Medicare covers the forms and the opt-out affidavit in more depth, and what documented care coordination actually looks like in the chart covers what has to be true clinically once enrollment is no longer the blocker.

Where this comes from. The ADA publishes “Should I Enroll in Medicare?” and separate step-by-step guides for participating and non-participating enrollment at ada.org. The specialty self-designation codes are defined in CMS Transmittal R12231CP (Change Request 13323), effective August 31, 2023 and implemented January 1, 2024. CMS’s own plain-language enrollment overview is published as MLN9658742 through the Medicare Learning Network. The underlying coverage rule enrollment exists to serve is 42 CFR 411.15(i)(3).