Medicare enrollment compliance is becoming increasingly strict, and many ordering and referring providers are facing unexpected deactivation due to inactivity, outdated PECOS records, or inactive NPI status. Under the 13-Month Rule, providers enrolled through CMS-855O can lose their ordering and referring privileges if their Medicare activity is not properly tracked through Part B claim attribution.
For physicians, eligible professionals (EPs), and certifying physicians, even a minor enrollment issue can lead to claim denials, reimbursement delays, and compliance risks.
In this guide, we’ll explain how the rule works, what 42 CFR 424.547 means in practice, and the exact steps providers can take to keep their PECOS O/R record active and avoid CMS-855O deactivation.
What Is the 13-Month Rule in Medicare Enrollment?
The 13-Month Rule is a Medicare enrollment compliance policy that allows CMS to deactivate ordering and referring providers who show no qualifying Medicare activity for an extended period. In simple terms, if a provider enrolled through CMS-855O does not appear on Medicare claims as an ordering, referring, or certifying provider, CMS may consider the enrollment inactive and deactivate the record.
The purpose of this rule is to maintain enrollment accuracy, reduce fraudulent activity, and ensure only actively participating providers remain eligible to order or certify Medicare services. CMS monitors provider activity through claim submissions, PECOS enrollment data, and Part B claim attribution.
It is important to understand that deactivation is different from revocation. Deactivation temporarily removes a provider’s ability to order or refer Medicare services, while revocation is a more serious enforcement action that can terminate Medicare participation entirely.
For many providers, deactivation happens without realizing their ordering activity was not properly linked to their PECOS O/R record or NPI. This is why regular enrollment monitoring is critical.
CMS-855O Enrollment
CMS-855O is the Medicare enrollment application used by providers who order, certify, or refer services for Medicare beneficiaries but do not bill Medicare directly. Instead of receiving reimbursements themselves, these providers support services such as DME orders, imaging referrals, lab testing, and home health certifications.
Common professionals who use CMS-855O include:
- Physicians
- Residents and fellows
- Nurse practitioners
- Clinical nurse specialists
- Physician assistants
To participate in Medicare ordering and referring activities, providers must qualify as an Eligible Professional (EP). An EP is a healthcare professional authorized by CMS to order, certify, or refer Medicare-covered services. Their enrollment information must remain active and accurately maintained in PECOS.
For example, a certifying physician signing a home health order must have:
- An active NPI
- A valid PECOS O/R record
- Proper CMS-855O enrollment status
If any of these records become inactive, Medicare claims tied to that provider may be rejected or delayed.
What Triggers CMS-855O Deactivation?
One of the most common causes of CMS-855O deactivation is prolonged inactivity. If a provider does not appear on Medicare claims as an ordering or referring provider within the monitoring period, CMS may deactivate the enrollment automatically.
Another major trigger is an incomplete or outdated PECOS O/R record. PECOS stores enrollment data for ordering and referring providers, and even minor inconsistencies can create compliance issues. Incorrect addresses, expired licensure information, or missing updates can all place the record at risk.
Inactive NPI status is another frequent problem. When an NPI becomes inactive or does not properly align with PECOS records, Medicare systems may fail to validate the provider during claims processing. This often leads to claim denials for DME suppliers, home health agencies, and diagnostic service providers.
Common triggers for deactivation include:
- No recent Medicare ordering activity
- Inactive NPI status
- Missing PECOS updates
- Unverified provider credentials
- Revalidation failures
- Claim attribution issues under Part B
Because Medicare systems rely heavily on automated verification, providers should routinely review their PECOS enrollment and ensure their ordering activity is correctly appearing on claims.
Part B Claim Attribution
Part B claim attribution is the process CMS uses to track provider activity through Medicare claims. Even if an ordering or referring provider does not bill Medicare directly, their NPI must still appear correctly on claims to confirm active participation in Medicare services.
CMS uses this claim activity to determine whether a provider enrolled through CMS-855O remains active. If a provider’s information is missing, inaccurate, or rarely submitted on claims, CMS may classify the enrollment as inactive and begin the deactivation process.
For example, when a physician orders durable medical equipment (DME), imaging, or laboratory services, their NPI is attached to the Medicare Part B claim. CMS then attributes that activity to the provider’s PECOS O/R record. If the system cannot validate the NPI or enrollment record, the claim may be denied.
Here’s how claim attribution typically works:
| Claim Role | Billing Provider | Ordering/Referring Provider |
| Receives payment | Yes | No |
| Must appear in PECOS | Yes | Yes |
| Uses CMS-855O | No | Yes |
| Impacts 13-Month monitoring | Limited | High |
Many providers assume clinical activity alone protects their enrollment status. However, CMS only recognizes activity that is properly reflected through Medicare claims and linked to an active PECOS record.
Who Is Considered a Certifying Physician?
A certifying physician is a healthcare provider authorized to certify that a Medicare patient qualifies for specific medical services or equipment. These certifications are commonly required for:
- Home health services
- Hospice care
- Durable medical equipment (DME)
- Therapy-related treatment plans
Under Medicare guidelines, the certifying physician must maintain active enrollment status and meet ordering and referring requirements. This includes having:
- An active NPI
- A valid PECOS O/R record
- Accurate CMS-855O enrollment information
For instance, if a physician certifies a patient for home health services but their PECOS enrollment is inactive, the associated Medicare claims may be denied even if the medical documentation is correct.
To remain compliant, certifying physicians should:
- Regularly verify PECOS enrollment
- Keep NPI information updated
- Ensure Medicare claims correctly reflect their ordering activity
- Monitor revalidation notices from CMS
Failure to maintain active enrollment can disrupt reimbursements for both providers and healthcare organizations.
What Does 42 CFR 424.547 Say?
42 CFR 424.547 is the federal regulation that gives CMS the authority to deactivate Medicare enrollment records when providers fail to meet enrollment requirements or maintain sufficient activity. The regulation is designed to strengthen Medicare program integrity and reduce improper billing activity.
In practical terms, the rule allows CMS to deactivate ordering and referring providers who:
- Show prolonged inactivity
- Fail to maintain accurate enrollment records
- Do not comply with Medicare enrollment requirements
- Have incomplete or outdated PECOS information
For providers enrolled through CMS-855O, this regulation directly impacts their ability to order, certify, or refer Medicare-covered services. Once deactivated, providers may experience:
- Claim denials
- Delayed patient services
- Interrupted referral workflows
- Reimbursement complications
Although the regulation is written in legal language, its operational meaning is straightforward: CMS expects ordering and referring providers to actively maintain their enrollment records and demonstrate ongoing Medicare activity through properly attributed claims.
Signs Your Provider Record May Be at Risk
Many providers do not realize their enrollment status is at risk until claims begin getting denied. Because CMS relies on automated verification systems, even small enrollment inconsistencies can trigger compliance issues.
Some of the most common warning signs include:
- Rejected Medicare claims
- Inactive NPI status notifications
- PECOS mismatch errors
- DME claim denials
- Home health certification rejections
- Missing ordering/referring provider edits
- CMS revalidation notices
Providers should also monitor whether their ordering activity is consistently appearing on Medicare Part B claims. In some cases, providers remain clinically active but fail CMS activity checks because their NPI is missing or incorrectly submitted on claims.
How to Prevent Ordering and Referring Provider Deactivation
Preventing deactivation starts with proactive enrollment management. Providers and healthcare organizations should routinely monitor their Medicare enrollment records to ensure all information remains accurate and active.
Monitor PECOS Regularly
Review PECOS records frequently to confirm:
- Active ordering/referring status
- Correct practice information
- Updated licensure details
- Accurate reassignment data
Even minor discrepancies can affect Medicare claim validation.
Maintain Medicare Claim Activity
CMS evaluates provider activity through claim submissions. Providers should ensure their NPI consistently appears on Medicare claims tied to ordering, referring, or certifying services.
Keep NPI Information Updated
An inactive or outdated NPI can immediately impact Medicare processing. Providers should regularly verify:
- Practice address
- Taxonomy codes
- State licensure
- Contact details
Complete Revalidation on Time
CMS periodically requires providers to revalidate enrollment information. Missing deadlines can lead to automatic deactivation.
Audit Referral and Certification Workflows
Healthcare organizations should routinely audit:
- Claim attribution accuracy
- Referral documentation
- Ordering physician identifiers
- Billing system integrations
Strong internal compliance processes significantly reduce the risk of CMS-855O deactivation.
What to Do If Your CMS-855O Enrollment Is Deactivated
If a provider’s CMS-855O enrollment becomes deactivated, immediate action is necessary to restore Medicare ordering and referring privileges. Delays in reactivation can result in ongoing claim denials and interruptions in patient care services.
Step 1: Identify the Cause of Deactivation
Review CMS correspondence and verify whether the issue involves:
- Inactivity
- Missing revalidation
- PECOS record discrepancies
- Inactive NPI status
Understanding the root cause helps streamline the reactivation process.
Step 2: Review Your PECOS O/R Record
Log into PECOS and confirm that all enrollment information is complete and accurate. Pay close attention to:
- Practice addresses
- Licensure data
- Specialty information
- Ordering/referring status
Step 3: Update NPI Information
Ensure the provider’s NPI remains active and matches the PECOS enrollment record. Inconsistencies between NPPES and PECOS are a common source of claim issues.
Step 4: Submit Reactivation or Enrollment Updates
Providers may need to:
- Reactivate CMS-855O enrollment
- Submit updated enrollment documentation
- Complete Medicare revalidation requirements
Processing timelines vary depending on the Medicare Administrative Contractor (MAC).
Step 5: Monitor Claims and CMS Responses
After reactivation, providers should closely monitor Medicare claims to confirm that ordering and referring activity is processing correctly and appearing under Part B claim attribution.
A structured compliance process can help providers avoid repeated deactivation issues and maintain uninterrupted Medicare participation.
Common Mistakes Providers Make
Many CMS-855O deactivations occur because providers assume their enrollment records are being maintained automatically. In reality, Medicare enrollment compliance requires continuous monitoring and regular updates.
One common mistake is assuming clinical activity alone counts as Medicare activity. CMS only tracks activity that appears correctly on Medicare claims through proper Part B claim attribution. If the provider’s NPI is missing or incorrectly submitted, CMS may still classify the record as inactive.
Another major issue is failing to update PECOS records after changes such as:
- New practice locations
- Updated licensure
- Taxonomy modifications
- Organizational restructuring
Providers also frequently ignore revalidation notices or delay responding to Medicare Administrative Contractor (MAC) requests. Even short delays can lead to CMS-855O deactivation and claim interruptions.
Additional mistakes include:
- Not monitoring inactive NPI status
- Delegating enrollment oversight without audits
- Using outdated provider information in billing systems
- Failing to review referral workflows regularly
Avoiding these errors requires a proactive compliance strategy supported by both providers and administrative teams.
Best Practices for Healthcare Organizations and RCM Teams
Healthcare organizations and revenue cycle management (RCM) teams play a critical role in preventing ordering and referring provider deactivation. A centralized compliance process can significantly reduce claim denials and enrollment disruptions.
Conduct Routine PECOS Audits
Organizations should regularly review provider enrollment records to ensure:
- Active PECOS O/R status
- Accurate provider demographics
- Valid licensure information
- Correct ordering/referring permissions
Quarterly audits are often the most effective approach.
Monitor Claim Attribution
RCM teams should verify that ordering and referring provider NPIs are correctly appearing on Medicare Part B claims. Even minor billing system errors can prevent CMS from recognizing provider activity.
Maintain NPI Accuracy
Keeping NPI records synchronized with PECOS is essential. Organizations should establish internal workflows for updating:
- Practice addresses
- Specialty codes
- Contact information
- Credentialing changes
Create Enrollment Tracking Systems
Using automated tracking systems can help organizations monitor:
- Revalidation deadlines
- Enrollment expiration risks
- CMS notifications
- Claim rejection trends
Strengthen Cross-Team Communication
Credentialing, billing, compliance, and provider management teams should work together to quickly identify enrollment issues before they affect claims processing.
Organizations that actively manage Medicare enrollment compliance are better positioned to prevent costly disruptions and maintain uninterrupted provider participation.
Final Thoughts
The 13-Month Rule has made Medicare enrollment compliance more important than ever for ordering and referring providers. Even experienced physicians and healthcare organizations can face CMS-855O deactivation due to inactive NPI status, outdated PECOS O/R records, or missing claim attribution activity.
By proactively monitoring enrollment records, maintaining accurate provider data, and ensuring consistent Medicare claim activity, providers can reduce the risk of deactivation and avoid costly claim disruptions. Understanding how CMS tracks ordering and referring activity under 42 CFR 424.547 is essential for maintaining uninterrupted Medicare participation.
For healthcare organizations, compliance is no longer just an administrative task; it is a critical part of protecting revenue, preventing denials, and ensuring smooth patient care operations.
