Introduction
In medical billing, especially when it comes to Durable Medical Equipment (DME), orthotics, and prosthetics, accurate claim submission is essential for providers to receive timely and appropriate reimbursement. As part of this process, M-codes are used as important billing indicators during claims processing, acting as guides and validations. Among these, the M11 modifier holds particular importance.
The M11 code is used to indicate that the billing is based on the geographic location of the patient, specially their zip code. Medicare and other insurers may use this information to determine the appropriate payment rates or regional policies that apply. Because reimbursement policies can vary by area, using the correct modifier based on a patient’s zip code ensures compliance with payer requirements and helps prevent delays or denials.
For billing experts who handle claims with regional guidelines or work across different jurisdictions, it is important for them to know how to use the M11 modifier appropriately.
1. What is the M11 Code?
The M11 code communicates a specific message: “DME, orthotics, and prosthetics must be billed to the DME carrier who services the patient’s zip code.” This code appears when claims for these supplies or equipment are sent to the wrong Medicare Administrative Contractor (MAC).
Medicare divides the United States into distinct geographic regions, each assigned to a specific DME MAC responsible for processing claims from that area. The fundamental principle of M11 is that claims must be directed to the correct regional carrier based on where the patient lives—not where the provider operates.
DME MAC Jurisdictions and Geographic Assignments
Medicare assigns each zip code in the United States to one of four DME MAC jurisdictions:
Jurisdiction | Contractor | States/Territories Covered |
Jurisdiction A | Noridian Healthcare Solutions | Connecticut, Delaware, Maine, Massachusetts, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont |
Jurisdiction B | CGS Administrators | Illinois, Indiana, Kentucky, Michigan, Minnesota, Ohio, Wisconsin |
Jurisdiction C | CGS Administrators | Alabama, Arkansas, Colorado, Florida, Georgia, Louisiana, Mississippi, New Mexico, North Carolina, Oklahoma, Puerto Rico, South Carolina, Tennessee, Texas, U.S. Virgin Islands, Virginia, West Virginia |
Jurisdiction D | Noridian Healthcare Solutions | Alaska, Arizona, California, Hawaii, Idaho, Iowa, Kansas, Missouri, Montana, Nebraska, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, Wyoming, American Samoa, Guam, Northern Mariana Islands |
Note: This table reflects current assignments as of 2024. Always verify current jurisdictions as they may change periodically.
2. Billing Challenges & Common Denials Related to M11
When claims receive an M11 code rejection, several common errors typically occur:
Provider-Location Based Submissions
- Submitting claims to the MAC covering the provider’s location instead of the patient’s zip code
- Multi-state providers using a single submission process for all patients regardless of location
- Failing to update billing systems when patients move to new zip codes
Jurisdiction Misidentification
- Confusion about which MAC handles specific zip codes, especially in border areas
- Not keeping up with periodic reassignments of zip codes to different jurisdictions
- Misunderstanding jurisdiction rules for traveling patients or those with multiple residences
System Configuration Issues
- Practice management software not configured to route claims based on patient zip code
- Incorrect Medicare jurisdiction tables in billing systems
- Automated processes that don’t account for jurisdiction requirements
3. Impact of M11 Denials
Overlooking the M11 requirement can lead to more than just a rejected claim—it can significantly impact the provider’s financial operations:
- Payment Delays: When claims are sent to the wrong MAC, they’re denied with an M11 code, requiring resubmission to the correct carrier and extending the payment timeline by weeks.
- Administrative Burden: Each rejected claim necessitates staff time for research, correction, and resubmission.
- Cash Flow Disruption: Repeated denials due to M11 errors can slow down revenue cycles, causing strain on a provider’s cash flow and disrupting day-to-day financial stability.
- Timely Filing Risks: If claims are submitted incorrectly again and again and not resolved before filing the deadlines, the practice may lose reimbursement opportunities totally.
4. Solutions and Best Practices
Medical billing teams can implement specific strategies to avoid M11 denials:
ZIP Code Verification Protocols
- Verify the patient’s current residential zip code at each visit
- Implement address verification technology in registration systems
- Create alerts when patients report address changes
MAC Jurisdiction Tools
- Use Medicare’s online lookup tools to determine which MAC services each patient’s zip code
- Develop internal reference guides mapping zip codes to appropriate MACs
- Set calendar reminders to check for Medicare jurisdiction updates quarterly
Billing System Configuration
- Configure practice management systems to flag potential jurisdiction mismatches
- Create jurisdiction-specific billing queues
- Implement automated pre-submission checks for appropriate MAC routing
Staff Training Programs
- Educate billing staff about the importance of patient zip code in DME billing
- Train registration personnel to collect and verify accurate address information
- Develop quick reference guides for common jurisdiction questions
5. Case Study: Resolving Persistent M11 Denials
A home medical equipment provider operating in a metropolitan area serving patients across state lines experienced a 23% denial rate with M11 codes appearing frequently.
Challenge: The billing team was submitting all claims to the MAC covering their office location but did not verify each patient’s jurisdiction.
Investigation:The analysis showed that 31% of their patients resided in zip codes falling under a different MAC jurisdiction than the provider’s own location.
Solution Implementation:
- Modified their intake process to prominently record patient zip codes
- A zip code tool system integrated to the billing software for easy reference
- Established a pre-submission review step specifically checking MAC jurisdiction
- Reorganized billing workflow to group claims by MAC jurisdiction
Results:
- Within two months the M11 denial was decreased by 97%
- The average payment days were reduced by 12 days.
- Staff time spent on resubmissions decreased by 28 hours monthly
- Fewer billing issues improved the satisfaction of the patient.
6. How to Verify the Correct DME MAC
To determine the appropriate DME MAC for claim submission, use these resources:
- Medicare’s DME MAC Jurisdiction Lookup Tool: Available through the Medicare website, this tool allows you to enter a patient’s zip code and receive the correct jurisdiction assignment.
- MAC Websites: Each DME MAC maintains current lists of zip codes within their jurisdiction.
- DME MAC Interactive Voice Response Systems: Many MACs offer phone systems where you can verify jurisdiction by entering a zip code.
- Supplier Manuals: Official Medicare supplier manuals include jurisdictional maps and requirements.
7. M11 in Relation to Other M-Codes
Understanding how M11 relates to other common M-codes helps billing staff interpret denial patterns:
Code | Description | Relationship to M11 |
M9 | “The claim was processed according to the jurisdiction’s fee schedule.” | Often appears after correcting an M11 issue, indicating proper jurisdiction processing |
M10 | “Equipment purchased is too expensive or frequent.” | May appear alongside M11 if equipment is also questioned for frequency/cost |
M23 | “Missing/incomplete/invalid patient identification” | Can compound M11 issues if patient information is also problematic |
M27 | “The patient has been relieved of liability…” | May appear with M11 when addressing patient responsibility for misdirected claims |
8.Documentation Best Practices
To support proper MAC jurisdiction assignment and avoid M11 denials, maintain thorough documentation including:
- Patient Address Verification: Document the process used to verify current patient address and zip code
- Change of Address Records: Maintain a clear history of patient address changes with effective dates
- MAC Jurisdiction Determination: Note which resources were used to verify the correct MAC jurisdiction
Delivery Location Details: For shipped items, document both the patient’s billing address and the actual delivery location
Conclusion
MACs that serve the zip code of the patient are responsible for billing DME, orthotics, and prosthetics. The M11 code represents the rule that requires claims to be sent to the MAC that services the patient’s zip code.By understanding this requirement and implementing appropriate verification processes, medical billing teams can:
- Direct claims to the correct jurisdiction the first time
- Reduce denial rates and resubmission work
- Accelerate payment cycles
- Improve overall billing efficiency
Verifying patient zip codes and correctly assigning Medicare Administrative Contractor (MAC) jurisdictions is essential for a smooth billing workflow. For suppliers of medical equipment and supplies, getting the jurisdiction right not only assures compliance but also supports frequent cash flow. While the process of verifying jurisdictions may add a few extra steps to billing, it significantly reduces the chances of claim denials. As a result, providers benefit from faster reimbursements and fewer delays, helping to maintain financial stability in day-to-day operations.