Medicare Provider Enrollment
Medicare provider enrollment is the process of registering with Medicare through PECOS (or paper CMS-855 forms) so claims can be paid. Clean applications typically process in 45 to 90 days, and physicians can bill retrospectively up to 30 days before their effective date. Enrollment is separate from and parallel to commercial credentialing.
- System
- PECOS (or paper CMS-855)
- Typical processing
- 45–90 days for clean applications
- Retro billing
- Up to 30 days pre-effective-date (90 in disasters)
- Output
- Approval letter + PTAN per location
What are the steps to enroll in Medicare?
- NPI first: the provider needs a Type 1 NPI (and the entity a Type 2) with accurate taxonomy in NPPES, because PECOS validates against it.
- I&A access: set up Identity & Access credentials and staff surrogacy so someone can actually work the application in PECOS.
- File the application: 855I equivalent for the individual, 855B for the group, reassignment linking the two, plus CMS-588 EFT and supporting documents matching IRS records exactly.
- Respond to development requests within the deadline (typically 30 days) or the application is rejected and you start over.
- Receive approval: the MAC issues an approval letter with the PTAN and effective date; only then release held claims.
What are the Medicare participation options?
Three, and they change the economics. Participating (PAR): accept assignment on all claims, get 100% of the fee schedule, patients' supplemental plans pay smoothly; this is the right answer for nearly every practice. Non-participating: paid on a fee schedule 5% lower, may balance-bill up to the limiting charge (115% of the non-PAR amount), collects from patients rather than Medicare on unassigned claims, and generates constant patient friction. Opt-out: private contracts with Medicare patients, no Medicare billing at all for two-year cycles, common only in psychiatry, concierge care, and some surgical niches.
The PAR decision window runs annually (mid-November through December 31, effective January 1), so a mid-year change of heart waits for the next cycle.
How long does enrollment take, and what does the delay cost?
Plan on 45 to 90 days for a clean electronic application, longer for paper, incomplete filings, or high-risk categories. The cash-flow math: a physician generating $18,000 a month in Medicare allowed charges who starts seeing patients with no application on file waits out the full processing time with unbillable visits beyond the 30-day retrospective window. Filing 90 days before the start date turns the same timeline into zero lost revenue. That difference, purely administrative, is often $20,000 to $40,000 per hire; run your own scenario through the credentialing calculator.
At 2026 rates every held claim is real money: a 99214 at roughly 2.62 total RVUs times the $33.4009 conversion factor is about $87.50 allowed, and a full patient day is 15 to 20 of those.
What does it take to stay enrolled?
Enrollment is a living record, not a one-time application. Revalidation comes due roughly every 5 years (3 for DMEPOS). Changes must be reported on deadline: ownership changes and adverse legal actions within 30 days, most other changes within 90. CMS may deactivate billing privileges after 12 months without claims, which quietly ambushes per-diem and rarely-billing providers. And reactive fixes are slow, so calendar the obligations instead. If nobody in the office owns this calendar, that is exactly the gap our provider credentialing service exists to fill.
Frequently asked questions
The PTAN (Provider Transaction Access Number) is the Medicare-internal number your MAC assigns at enrollment, per provider per group per location. The NPI is the national identifier that goes on claims. You use the NPI to bill and the PTAN to authenticate: portal access, IVR calls, and correspondence with the MAC all require the PTAN.
855I for individual physicians and practitioners (which now also handles reassignment of benefits, replacing the retired 855R's standalone role for most uses), 855B for group practices and certain suppliers, 855O for clinicians who only order and refer, and 855S for DMEPOS suppliers. In PECOS you answer questions and the system builds the right application.
Physicians and non-physician practitioners pay no application fee. Institutional providers and suppliers (including DMEPOS) pay a CMS application fee that adjusts annually, and certain categories also face risk-based screening including fingerprinting for high-risk enrollment types like new home health agencies and DMEPOS suppliers.
Yes, strategically: file the application, see patients, hold the claims, and bill after approval. The effective date is generally the later of the filing date or the first service date, and physicians may bill retrospectively up to 30 days before the effective date. What you cannot do is bill under another physician's number while waiting; that is a false claim.
Sources & further reading
Reviewed by the ImmediCare Solutions RCM team
Certified billers and coders handling claims across 50+ specialties nationwide. This entry is reviewed against current payer policy and CMS rules. Last review: Jul 5, 2026.
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