The Medicare enrollment reference for providers.
Which form, in what order, and how long it takes. Step-by-step guides to every CMS enrollment application, PECOS walkthroughs, NPI registration, and this year's rule changes — written for physicians, therapists, behavioral health, EMS, and DME suppliers.
Mae — the enrollment guide built into every page
Find your enrollment path
Each provider type has different CMS requirements, forms, and timelines. Start with yours.
Medicare enrollment for physicians (MD/DO) — CMS-855I, PECOS, group practice enrollment, reassignment, opt-out, and Medicare Advantage credentialing.
View guides →The complete Medicare enrollment guide for ABA therapy providers — BCBAs, BCaBAs, and ABA organizations. Forms, steps, 2026 coverage update
View guides →Complete Medicare enrollment guide for physical therapists — individual and group PT enrollment, key forms, KX threshold rules
View guides →Medicare enrollment for all behavioral health providers — clinical psychologists, LCSWs, LMHCs, MFTs, psychiatrists, and psychiatric NPs..
View guides →Medicare enrollment guide for EMS agencies, ground ambulance suppliers, and air medical providers — required forms, supplier standards
View guides →Complete Medicare enrollment guide for DME and DMEPOS suppliers — the CMS-855S, surety bond, accreditation requirements, supplier standards, and billing basics.
View guides →How Medicare provider enrollment works
Five steps, in order. Most individual providers complete the process in 30–60 days via PECOS.
Get your NPI
Individual providers need a Type 1 NPI; organizations need a Type 2. Register at NPPES before anything else. Guide →
Pick the right application
CMS-855I for individuals, CMS-855B for groups, CMS-855R to link the two. Your provider type and structure decide the set. Guide →
File in PECOS
Online filing is faster than paper — typically 30–45 days versus 60–90. Upload licenses, banking (CMS-588), and ownership info. Guide →
Respond to development requests
Your MAC will ask for clarifications. Unanswered requests are the most common cause of rejection. Guide →
Approval: PTAN + effective date
Billing starts on the effective date CMS assigns — claims for earlier dates of service are denied. Guide →
Your Medicare enrollment guide
Not sure where to start? Mae is a Medicare enrollment guide built into this site. She knows what page you're on, understands your provider type, and can walk you through the right enrollment path — then connect you with Metolius Health when you're ready for expert help.
Watch Mae guide a BCBA through Medicare enrollment
Mae knows which page you're on, your provider type, and the exact forms you need. She guides providers to the right enrollment path — then naturally introduces the Metolius Health audit when they're ready for expert help.
The complete enrollment library
Every major enrollment form with step-by-step instructions and risk flags.
Complete walkthroughs for the CMS online enrollment portal.
Type 1 vs. Type 2, NPPES walkthrough, group practice NPI.
How Medicare Advantage plans operate and how to contract with them.
Group practice enrollment, reassignment of benefits, FQHC/RHC designation.
ABA coverage, LMHC approval, KX threshold, EMS billing changes.
Frequently asked
What is PECOS and do I have to use it?
PECOS (Provider Enrollment, Chain, and Ownership System) is CMS's online portal for Medicare enrollment. Most individual and organizational providers can enroll online via PECOS instead of submitting paper CMS-855 forms. PECOS is generally faster — paper submissions can take 60–90 days; PECOS submissions often process in 30–45 days.
What's the difference between a Type 1 and Type 2 NPI?
A Type 1 NPI identifies an individual provider (a specific PT, BCBA, or physician). A Type 2 NPI identifies an organization (a practice, clinic, or group). Individual providers get a Type 1. Their employer or group practice gets a Type 2. Both are often needed before Medicare enrollment can proceed.
How long does Medicare enrollment take?
PECOS submissions for individual providers (CMS-855I): 30–60 days. Organizational enrollment (CMS-855B): 60–90 days. DMEPOS suppliers: 60–120 days. New provider types (like ABA in 2026) may take longer while MACs process the new credential type. Plan accordingly — Medicare billing doesn't start until enrollment is approved and a billing date is established.
Can I bill Medicare retroactively for services before my enrollment was approved?
Generally no. Medicare does not backdate billing privileges to your application submission date — billing begins on the effective date CMS assigns, typically no earlier than your application completion date. Claims for dates of service before your effective date are denied.
How often do I have to revalidate my Medicare enrollment?
Most individual providers and organizations revalidate every 5 years; high-risk provider types such as DMEPOS suppliers and home health agencies revalidate every 3 years. CMS sends a notice about 180 days before your deadline — to the correspondence address on file. Missing the deadline deactivates your billing privileges retroactively, with no grace period.
What is reassignment of benefits (CMS-855R)?
Reassignment lets a group practice bill Medicare for an individually enrolled provider's services. The provider keeps their own CMS-855I enrollment; the CMS-855R transfers the right to receive payment to the group. Without an 855R on file for each provider, the group cannot bill for that provider — even if both are enrolled.
What's the difference between opting out and non-participation?
Non-participating providers stay enrolled in Medicare but don't sign the CMS-460 participation agreement — they can choose claim-by-claim whether to accept assignment. Opting out means leaving Medicare entirely via a formal affidavit and billing patients under private contracts. Opt-out is binding, and you cannot retroactively bill Medicare for the opt-out period.
Should I file in PECOS or use the paper CMS-855I?
For most providers, PECOS. It's faster (often 30–45 days versus 60–90 for paper), tracks application status, and pre-fills revalidations. Paper remains the right call only in a few specific situations — our comparison guide covers them.
I'm a new ABA provider. Where do I start with Medicare enrollment in 2026?
ABA providers newly eligible under the 2026 Medicare Part B coverage expansion should start with obtaining an individual NPI (Type 1), then enroll through PECOS using the CMS-855I (for individual BCBAs) or CMS-855B (for group practices). See our full ABA enrollment guide for the sequence and risk flags.
What is the free Medicare audit and who does it?
The free Medicare enrollment audit is offered by Metolius Health, our affiliated Medicare services partner. It reviews your current enrollment status, flags gaps or expired revalidations, checks for billing eligibility issues, and gives you a clear action plan. It's a conversation, not a sales pitch. Schedule it from the audit page.
See where your Medicare enrollment has gaps.
A revenue cycle assessment is a conversation, not a pitch. We look at your enrollment status, flag expiring revalidations, and tell you what to fix — at no cost.
Get your free Medicare audit