Medicare Enrollment

The process of registering as a Medicare provider through PECOS using the CMS-855 application forms, enabling a provider to bill Medicare for services rendered to Medicare beneficiaries.

Medicare enrollment is one of the most important credentialing processes you will go through because Medicare covers over 65 million Americans. If you see adults, a significant percentage of your patients will have Medicare coverage. The enrollment process starts in PECOS, CMS's online enrollment system. Individual providers submit a CMS-855I application. Group practices submit a CMS-855B. Institutional providers submit a CMS-855A. The application collects your identification information, education, licenses, practice locations, ownership details, and adverse action history. After you submit through PECOS, you must print the certification statement, sign it with a wet signature, and mail it to your Medicare Administrative Contractor. This is the one step that cannot be done entirely online. CMS has been working on eliminating this requirement, but as of 2026, it is still necessary. Your MAC processes the application and conducts verification. Processing times are typically 45 to 65 days but can be longer during peak periods. The MAC may send you a development request asking for clarification or additional documentation. Respond within 30 days or your application may be rejected. Once approved, you receive a welcome letter with your effective date and PTAN (Provider Transaction Access Number). Your effective date is the later of: the date you submitted your application or the date you began providing services at the enrolled practice location. You choose a participation status during enrollment. Participating providers accept assignment on all claims, meaning they accept Medicare's allowed amount as payment in full. Non-participating providers can choose to accept or decline assignment on each claim. Most providers choose participating status because it guarantees direct payment and higher allowed amounts. Medicare enrollment must be revalidated every five years. CMS sends a revalidation notice to your PECOS correspondence address. Miss the revalidation deadline and your billing privileges get deactivated. Set reminders and keep your correspondence address current. Start Medicare enrollment early. Even if you are not seeing Medicare patients yet, having an active enrollment gives you flexibility and eliminates the delay when your first Medicare patient walks in.