Medicare Provider Enrollment & Credentialing
Medicare is the federal health insurance program administered by the Centers for Medicare & Medicaid Services (CMS), covering approximately 65 million Americans age 65 and older, those with certain disabilities, and individuals with end-stage renal disease. Medicare enrollment is the foundation of any practice's payer mix — it is often required before downstream commercial payers will credential a provider, and it unlocks access to the largest single government health program in the United States.
Medicare enrollment is managed through PECOS, the Provider Enrollment, Chain, and Ownership System. The online PECOS application has largely replaced paper-based CMS-855 forms, though paper applications are still accepted. Each Medicare Administrative Contractor (MAC) serves a specific geographic region, and processing times vary by MAC. The Palmetto GBA MAC (serving the southeastern United States) and the Noridian MAC (serving the western states) are among the larger contractors.
A critical concept for Medicare enrollment is the "opt-out" versus "participating" versus "non-participating" distinction. Providers who enroll as participating agree to accept Medicare's fee schedule as payment in full. Non-participating providers can still see Medicare patients but are reimbursed at 95% of the fee schedule. Providers who opt out entirely cannot bill Medicare at all (except in emergencies) for two years. The vast majority of providers benefit from full participation.
Medicare does not require CAQH, as it maintains its own enrollment database through PECOS. However, many commercial payers use Medicare's PECOS verification as part of their credentialing process, making clean and complete Medicare enrollment important for overall provider data hygiene.
Payer Overview
- Parent Company:
- Centers for Medicare & Medicaid Services (CMS)
- Type:
- Government
- Enrollment Portal:
- PECOS (Provider Enrollment, Chain, and Ownership System)
- CAQH Required:
- No
Medicare Credentialing Process
Obtain or verify your National Provider Identifier (NPI) through NPPES (nppes.cms.hhs.gov).
Create or log in to your CMS Identity Management (IDM) account at https://idm.cms.gov.
Access PECOS and complete Form CMS-855I (individual physician/practitioner) or CMS-855B (group practice).
Submit all required supporting documentation including state license, DEA, malpractice, and practice location information.
Your Medicare Administrative Contractor (MAC) processes the application; MACs vary by state.
Receive your Medicare par approval letter and Provider Transaction Access Number (PTAN); confirm your effective date.
Required Documents
Average Credentialing Timeline
60–90 days
Typical time from complete application submission to Medicare par approval
States Available
Medicare operates in 51 states. State-specific credentialing pages with local requirements, medical board contacts, and Medicaid program details are available for many of these states.
Frequently Asked Questions
What is PECOS and why do I need it?
PECOS (Provider Enrollment, Chain, and Ownership System) is CMS's online system for Medicare enrollment. All providers who wish to bill Medicare must be enrolled in PECOS. Many commercial payers and hospitals also check PECOS as part of their credentialing process, making PECOS enrollment foundational to any practice's payer strategy.
How long does Medicare enrollment take?
Medicare enrollment through a Medicare Administrative Contractor typically takes 60–90 days for complete online applications. Paper applications generally take longer. Incomplete applications or those requiring additional documentation can take 120+ days. Starting Medicare enrollment early — before a practice opens or a provider joins — is strongly recommended.
What is the difference between Medicare participation and opt-out?
Participating providers accept Medicare's allowed amount as full payment. Non-participating providers can still bill Medicare but receive 95% of the fee schedule and can bill patients a limited amount above Medicare's rate. Providers who opt out cannot bill Medicare for two years and must give patients written notice. Most providers benefit from full participation status.
Credentialing in States Where Medicare Operates
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Reviewed by Arctic Health Team , Credentialing Specialists
Last reviewed: April 2026
Information on this page reflects our experience as of April 2026. Credentialing requirements, payer processes, and state regulations may change. Contact us or check the relevant state medical board and payer websites for the most current requirements. This content is for informational purposes only and does not constitute legal or professional advice.