TL;DR — The CMS-855I is Medicare’s enrollment application for individual providers — physicians, NPs, PAs, therapists, psychologists, LCSWs, and other Part B practitioners billing under their own NPI. File it online in PECOS (typically 30–60 days) or on paper to your MAC (60–90 days). Approval assigns your PTAN, and billing starts on the effective date CMS assigns — claims for earlier dates of service are denied. The CMS-855I is the primary Medicare enrollment application for individual providers seeking billing privileges. If you’re a physician, nurse practitioner, physician assistant, physical therapist, occupational therapist, speech-language pathologist, clinical psychologist, licensed clinical social worker, CRNA, or any other individual non-institutional provider — and you want to bill Medicare for your services — this is your form.
Filing the CMS-855I results in a Provider Transaction Access Number (PTAN) and, assuming approval, active Medicare billing privileges under your individual National Provider Identifier (NPI).
Who needs the CMS-855I
You need the CMS-855I if you are:
- A physician (MD, DO) seeking individual Medicare enrollment
- A non-physician practitioner (NP, PA, CNM, CRNA, CNS)
- A physical therapist in independent practice
- An occupational therapist in independent practice
- A speech-language pathologist in independent practice
- A clinical psychologist
- A licensed clinical social worker (LCSW)
- An audiologist
- A registered dietitian or nutrition professional
- A certified nurse-midwife
- An anesthesiologist assistant
- Any other Part B provider billing under their own individual NPI
You do not need the CMS-855I if:
- You only order or refer Medicare services (use CMS-855O instead)
- You are a group practice or organization (use CMS-855B)
- You are an institutional provider (hospital, SNF, HHA — use CMS-855A)
- You are a DMEPOS supplier (use CMS-855S)
Before you file: prerequisites
Complete these before you touch the CMS-855I:
- Active Type 1 NPI in NPPES. Your NPI must be assigned and the taxonomy code must match your enrollment specialty. If you don’t have an NPI yet, register at NPPES first.
- Current DEA registration (if applicable to your practice type)
- Current state license(s). License must be active in every state where you’ll see Medicare patients.
- Malpractice insurance information. CMS requires active professional liability coverage.
- Banking information for EFT. You’ll file the CMS-588 (Electronic Funds Transfer) at the same time or shortly after.
Step-by-step: Filing via PECOS (recommended)
Filing via PECOS is faster and provides real-time tracking. Full PECOS walkthrough →
Step 1: Access PECOS Go to pecos.cms.hhs.gov. Log in with your CMS I&A (Identity & Access Management) credentials. If you don’t have an I&A account, create one first.
Step 2: Start a new enrollment Select “Individual Enrollment” from your dashboard. Confirm your NPI and provider type. PECOS will pre-populate information from your NPPES record — verify it’s accurate before proceeding.
Step 3: Complete Section 1 — Identifying information
- Legal name (must match your NPI record exactly)
- Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN)
- Date of birth
- Home address
Step 4: Complete Section 2 — Practice location(s)
- Primary practice address
- Additional practice locations (if you practice at multiple sites)
- Specialty/taxonomy code for each location
Step 5: Complete Section 3 — Correspondence address Where CMS and your MAC will mail official notices. This is critical — missed revalidation notices go here.
Step 6: Complete Section 4 — Licensing and certification Enter all active state medical or professional licenses. Each license requires: state, license type, license number, effective date, expiration date.
Step 7: Complete Section 5 — Adverse legal history Disclose any adverse actions: convictions, license revocations, OIG exclusions, prior Medicare/Medicaid sanctions. Omitting disclosures is grounds for denial or revocation.
Step 8: Complete Section 6 — Managing employees List individuals with managing control of your practice (if applicable).
Step 9: Upload supporting documentation Required uploads vary by provider type but typically include: copy of current state license, copy of malpractice insurance declaration page, IRS Form CP-575 (if applicable), voided check or bank letter for EFT.
Step 10: Electronic signature PECOS allows electronic signature. After signing, your application enters the MAC review queue. You’ll receive a confirmation number.
Step-by-step: Filing via paper (when required)
Download the current version of the CMS-855I from cms.gov. Always use the current version — MACs reject outdated form versions.
- Print the form and complete all required sections (same sections as PECOS above)
- Attach all supporting documentation
- Wet-ink signature on the certification page
- Mail to your MAC’s enrollment processing address (not CMS directly — find your MAC at cms.gov/Medicare/Provider-Enrollment-and-Certification/MedicareProviderSupEnroll/downloads/mac-website-list.pdf)
⚠️ Risk flags
⚠️ Name mismatch between NPI and CMS-855I. Your legal name on the CMS-855I must match your NPI record in NPPES exactly. Even minor discrepancies (middle initial, suffix) can cause rejection. Verify your NPPES record before filing.
⚠️ Incomplete adverse legal history disclosure. Section 5 requires disclosure of all adverse actions. Omitting a prior exclusion, license action, or Medicare sanction — even if old or minor — is grounds for denial and potential fraud referral. When in doubt, disclose.
⚠️ Wrong taxonomy code. Your taxonomy code determines what services CMS will accept claims for. If you use a general taxonomy (e.g., “general practice”) when you should use a specialty taxonomy (e.g., “physical therapist”), you may be able to enroll but face claim denials. Verify your taxonomy against the CMS taxonomy list.
⚠️ Missing or expired license. CMS will verify your license with the state licensing board. If your license is expired at the time of application, your enrollment will be denied.
Common errors and how to avoid them
Error: Application returned as incomplete Cause: Missing required attachments, blank required fields, or unsigned certification. Fix: Use the PECOS checklist before submission. Attach every required document.
Error: NPI not found in system Cause: NPI was recently assigned and hasn’t propagated to CMS systems yet, or there’s a discrepancy in the NPI number entered. Fix: Wait 24–48 hours after NPI assignment before filing. Verify the 10-digit NPI number exactly.
Error: License verification failure Cause: MAC cannot verify your license with the state board (name mismatch, license on probation, expiration discrepancy). Fix: Contact your state licensing board to confirm the information they provide to third parties, then align your application to match.
Error: Taxonomy code mismatch Cause: Taxonomy entered in the application doesn’t match your NPPES taxonomy. Fix: Update your NPPES taxonomy first, then file the application.
Processing timeline
| Filing method | Typical processing time |
|---|---|
| PECOS electronic | 60–90 days (typical) |
| Paper CMS-855I | 90–180 days (typical) |
| Expedited processing (qualifying circumstances) | 15–30 days |
Processing times vary by MAC. Noridian, Novitas, CGS, WPS, and Palmetto GBA all have different workloads and average processing times. PECOS provides status updates — check status at 30, 60, and 90 days.
⚠️ Backdating: Medicare does not backdate billing privileges to your application submission date. Your billing privileges begin on the effective date CMS assigns, which is typically no earlier than your CMS-855I completion date. Claims submitted for services before your effective date will be denied.
What happens after submission
- MAC receives and logs the application. You’ll receive a confirmation letter or, for PECOS, a PECOS application ID.
- Development period. The MAC may contact you to request additional information or documentation (“development”). Respond within 30 days or the application is denied.
- Verification. MAC verifies licenses, taxonomy, NPIs, and performs background checks.
- Approval or denial. If approved, you receive a PTAN (Provider Transaction Access Number) and a Medicare enrollment letter with your effective date.
- Set up EFT and claims submission. If you haven’t filed CMS-588, do so now. Configure your billing system with your PTAN.
- Begin billing. Do not submit claims for dates of service before your effective date.
After approval: what to do next
- File CMS-855R if you’ll be reassigning benefits to a group practice
- File CMS-460 if you want to be a Medicare participating provider (recommended for most)
- File CMS-588 to activate EFT for direct deposit
- Verify your PECOS enrollment profile reflects your current practice location(s)
Related forms and pages
- CMS-855R — Reassignment of Medicare Benefits — required to bill through a group practice
- CMS-855B — Organization/Group Practice Enrollment — if your practice isn’t yet enrolled
- CMS-460 — Participating Provider Agreement
- CMS-588 — EFT Authorization
- PECOS vs. Paper: Which to Use
- PECOS Submit Enrollment Guide
Not sure if CMS-855I is the right form for your situation? Ask Mae → Want a professional review of your enrollment status? Free audit by Metolius Health →