Ordering and Referring Providers: Enrolling with CMS-855O
Physicians and other eligible professionals who order or certify Medicare Part A or B services for patients, without submitting Medicare claims themselves, must be enrolled in Medicare in an approved or opt-out status. This enrollment uses form CMS-855O. Three requirements must be met: an active individual (Type 1) NPI, enrollment in an approved or opt-out status, and membership in an eligible specialty type. If the ordering provider is absent from the claim or not on the Medicare eligibility list, the claim is denied.[1]
Many physicians and non-physician practitioners never submit Medicare claims directly. They work for government agencies, practice in federally funded clinics, have retired from active billing, or simply work in settings where their employer handles all claims. None of that exempts them from Medicare enrollment when they write orders or certifications for Medicare patients. This page explains the ordering and certifying enrollment pathway, who it applies to, and what happens when a claim lists an unenrolled provider.
What "Ordering and Referring" Means
Medicare Part B claims identify the professional who ordered or certified an item or service through the ordering/certifying provider field. CMS uses specific terms for these actions:[1]
- Providers order non-physician patient items or services, such as DMEPOS, clinical laboratory services, and imaging services.
- Providers certify patient home health services.
The health care industry uses "ordered," "referred," and "certified" interchangeably in everyday practice, but the Medicare program uses the term "ordering/certifying provider" as the precise designation. The phrase "ordering and referring" that appears in public CMS datasets follows the same concept.
Who Needs to Enroll via CMS-855O
Physicians and eligible professionals who order or certify Medicare Part A or B services but do not want to submit Medicare claims are eligible ordering/certifying providers. They must enroll in the Medicare program, but their enrollment is specifically for the purpose of ordering and certifying, not billing. Providers enrolled using CMS-855O cannot bill Medicare and will not receive Medicare payments for patient services, because they have no Medicare billing privileges.[1]
There is one important exception to the enrollment requirement: a provider who is already enrolled as a Part B billing provider can list themselves as the ordering/certifying provider on claims without re-enrolling through CMS-855O. The CMS-855O pathway is specifically for those who have no existing billing enrollment.[1]
Only individual (Type 1) NPIs qualify for ordering and certifying purposes. Organizational (Type 2) NPIs do not qualify and cannot be used on claims in the ordering/certifying provider field. If a claim lists an organizational NPI in that field, it will fail validation.[1]
The Three Requirements
All three must be met. A provider with a valid NPI and approved enrollment who falls outside the eligible specialty types cannot use CMS-855O. Similarly, an eligible specialty provider with no enrollment cannot have their NPI accepted on a claim even if the NPI itself is valid.
Eligible Specialty Types
CMS publishes a non-exhaustive list of physicians and eligible professionals who may enroll in Medicare solely for ordering or certifying. The following categories are explicitly included:[1]
- Department of Veterans Affairs employees
- Public Health Service employees
- Department of Defense or TRICARE employees
- Indian Health Service or Tribal Organization employees
- Federally Qualified Health Center, Rural Health Clinic, or Critical Access Hospital employees
- Licensed residents in an approved medical residency program (as defined at 42 CFR 413.75(b))
- Dentists, including oral surgeons
- Pediatricians
- Retired, licensed physicians
This list is not exhaustive. If you are unsure whether your specialty qualifies, review Section 4 of form CMS-855O or contact your MAC before submitting an enrollment application.[1] For dentists specifically, provider specialty codes are documented in a separate CMS reference.
Interns and Residents
Claims for items or services ordered or certified by licensed or unlicensed interns and residents require special handling. The claim must specify a teaching physician's NPI and name, not the intern's or resident's NPI.[1]
State-licensed residents occupy a slightly different position: they may enroll to order or certify and can be listed on claims directly, consistent with state law. If a state offers provisional licenses or otherwise permits residents to order or certify, CMS allows those residents to enroll. Check your state's licensing rules before submitting a CMS-855O for a resident who does not yet hold a full license.
What Triggers a Claim Denial
Claims that reference an ordering or certifying provider who lacks a valid individual NPI, or who is not enrolled in an approved or opt-out status, are denied by the MAC. The denial applies to the entity submitting the claim, not the ordering provider, which means a DMEPOS supplier or laboratory bears the financial consequence of an unenrolled ordering physician.[1]
The following claim types are denied when the ordering provider is missing or invalid:
The claim must have both a valid individual NPI and the eligible provider's name exactly as it appears in PECOS. A mismatch between the name on the claim and the name in PECOS, even a minor formatting difference, can cause denial.[1]
If a provider who is on the CMS Preclusion List prescribes a Medicare Part D drug, Part D drug plans will deny the prescription. The Preclusion List includes providers who have been revoked from Medicare or who have been excluded from federal health care programs. Even if a provider has a valid NPI and is technically eligible to order, being on the Preclusion List prevents Part D claims from going through.[1]
The Order and Referring Dataset
CMS publishes the Order and Referring dataset at data.cms.gov. This dataset is the authoritative public source for confirming whether a provider is currently enrolled and eligible to order or certify for Medicare patients. Appearing on the list confirms active enrollment status.[2]
Two additional datasets can help verify the status of pending applications:
- The Pending Initial Logging and Tracking Physicians dataset covers physicians whose ordering/certifying enrollment applications are under MAC review.
- The Pending Initial Logging and Tracking Non Physicians dataset covers non-physician practitioners in the same pending status.
Both are available at data.cms.gov. If a provider's name appears on a pending dataset but not yet on the Order and Referring list, their application has been received but not yet processed to an approved status.
What the Dataset Contains
The Order and Referring dataset is structured around a provider's NPI and name, plus a series of eligibility flags indicating which service categories the provider is approved to order or refer. Each record includes the following fields:[3]
| Field | What it indicates |
|---|---|
| NPI | The provider's individual Type 1 NPI |
| Last Name / First Name | Provider name as it appears in PECOS; the claim must match this exactly |
| Part B (Y/N) | Whether the provider can refer to Part B clinical laboratory and imaging services |
| DME (Y/N) | Whether the provider can order Durable Medical Equipment |
| HHA (Y/N) | Whether the provider can refer to Home Health Agency services |
| PMD (Y/N) | Whether the provider can order Power Mobility Devices |
| Hospice (Y/N) | Whether the provider can refer to Hospice services |
The flags are independent: a provider can be eligible to order DME but not Power Mobility Devices, for example. Billing entities and credentialing teams should check the specific flag that applies to the service category they are processing, not just confirm that the provider appears in the dataset at all.
How This Data Appears on NPI Profile
Every provider profile on NPI Profile that has a PECOS enrollment indicator draws from this same Order and Referring dataset. When a profile shows "Eligible to Order or Refer: Yes," the provider appears in the current CMS Order and Referring data with at least one active eligibility flag. The individual Part B, DME, HHA, PMD, and Hospice flags are also displayed where available, giving billers and credentialing teams a quick reference without leaving the lookup tool.
The dataset is updated on NPI Profile's weekly refresh cycle. For real-time verification, particularly for claims already in process or for eligibility questions where timing is critical, query the CMS Order and Referring dataset directly at data.cms.gov.
Check a provider's ordering and referring eligibility.Search by name or NPI to see the Order and Referring flags, Medicare participation status, and PECOS enrollment.
PECOS LookupSources
This guide is based on the following official government publications. NPI Profile summarizes official documentation for convenience; the source documents remain the authoritative reference.
- Centers for Medicare & Medicaid Services, Medicare Learning Network. Medicare Provider Enrollment (MLN9658742). 2026 edition. "Providers Who Solely Order or Certify" section: ordering/certifying terms, eligibility conditions, requirements 1 through 5, eligible specialty list, interns and residents, claim denial rules, and the Preclusion List.
- Centers for Medicare & Medicaid Services. Medicare Provider Enrollment (MLN9658742). Table 2: Options to Verify Your Current Enrollment Record Exists in PECOS, including references to the Order and Referring datasets and the Pending Initial Logging and Tracking datasets at data.cms.gov.
- Centers for Medicare & Medicaid Services. Order and Referring Data Dictionary. Defining the NPI, name, Part B, DME, HHA, PMD, and Hospice fields in the Order and Referring dataset.
