Medicare enrollment is the most important credentialing relationship most providers will ever have. It's also historically the most frustrating. The portal (PECOS) is unintuitive, the form options are confusing, the MACs are each a little different to work with, and the RTI (Return to Provider) notices can be cryptic at best.
I've personally managed hundreds of Medicare enrollments for clients across multiple MACs. Let me walk you through how we actually do this, not just the theory of it.
Step 1: Choose the Right Form — This Matters More Than People Realize
CMS has multiple 855 form types, and using the wrong one is one of the most common reasons applications get kicked back. Here's a quick decision guide:
Most physicians starting a new practice will need both a CMS-855I (individual) and a CMS-855B (group) submitted together, with the group enrollment done first. If the group TIN isn't enrolled before the individual, the individual application has nothing to reassign to.
Step 2: Use PECOS, But Know Its Quirks
The Provider Enrollment, Chain, and Ownership System is the online platform for Medicare enrollment at pecos.cms.hhs.gov. CMS strongly prefers PECOS over paper filing — paper adds 4–6 weeks minimum.
The system works reasonably well but has some known gotchas our team has learned the hard way:
- Create the account first, let it verify before you start the application. The identity proofing step can take 24–48 hours and if you just power through and submit without it completing, the application won't be fully authorized.
- Double-check the legal business name field. It must match your IRS CP-575 exactly — not your DBA, not a shortened version. Literally character for character.
- The EFT authorization form is separate. Many people don't realize you have to submit the banking information separately through the EFT process, not just in the main application. Missing this is a common RTI trigger.
Step 3: The Documents CMS Will Ask For
When you submit through PECOS, the MAC will also want certain documents uploaded or mailed depending on their specific requirements. Be ready with:
- Copy of current medical license for every state where you practice
- IRS CP-575 letter (EIN confirmation) with your exact legal name on it
- Voided check or bank letter for EFT enrollment — the check must match the TIN on the application
- Signed CMS-588 (EFT Authorization Agreement)
- Signed certification statement
- DEA registration (if prescribing or ordering controlled substances)
⚠️ The RTI (Return to Provider) trap: When the MAC sends an RTI, they email the contact on file. That email typically goes to whoever set up the PECOS account — which might be an admin who no longer works there, or a personal email nobody checks. We've seen applications sit for 60+ days without a response because nobody saw the RTI. Set up multiple contacts in PECOS and check for RTI notices every 2 weeks.
Step 4: Follow Up Like It's Your Job — Because It Is
Once your application is submitted, you'll get a Document Control Number (DCN). Write it down and put it somewhere visible. This is the reference number for every follow-up call to your MAC.
Our follow-up cadence: confirm receipt at Day 14, then call with the DCN every 7 business days. When we call, we don't just ask "what's the status?" We have all the provider's information ready and we ask specifically: Has this been assigned? Is it in committee review? Is there a pending RTI? That level of specificity gets better answers.
Average MAC processing time is 60–90 days in 2026. Some MACs are running faster, some slower. Track it actively and you'll know when something has stalled.
Medicare Enrollment Is Our Specialty
We handle PECOS submissions, MAC follow-up, RTI response, and revalidation management for healthcare providers across all 50 states. If you need Medicare enrollment done fast and right, that's exactly what we do.
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