MAC Audit Documentation Requirements
What Medicare Administrative Contractors actually request when auditing research billing. Includes sample documentation and response templates from institutions with zero findings.
What Triggers a MAC Audit
MAC audits of research billing typically result from: (1) data mining algorithms detecting billing patterns inconsistent with diagnosis codes, (2) whistleblower complaints, (3) random sampling programs, or (4) follow-up from prior findings at your institution.
Regardless of trigger, the documentation request follows a predictable pattern. Being prepared converts a stressful audit into a routine administrative exercise.
Common Documentation Requests
Medicare Coverage Analysis for each billed claim
What they want
The MCA grid showing routine vs research classification with NCD 310.1 rationale for each procedure
No MCA exists, or MCA doesn't match billed procedures
Complete MCA with procedure-level classification, NCD citation, and analyst signature
Protocol and budget documents
What they want
The specific protocol version and budget effective during the billing period
Providing current version instead of version effective at time of service
Archived protocol/budget with clear version number and effective date range
Clinical trial agreement (CTA)
What they want
Signed CTA showing which party (sponsor vs institution) bears each cost
CTA is silent on cost allocation or contradicts billing
Executed CTA with clear cost responsibility language for questioned items
Evidence of qualifying trial status
What they want
Documentation that trial meets NCD 310.1 criteria (FDA-regulated, IND, therapeutic intent)
No IND number, unable to demonstrate FDA regulation
ClinicalTrials.gov registration, IND letter, or IRB approval documenting trial type
Subject enrollment documentation
What they want
Proof that billed patient was enrolled in trial at time of service
Charges billed before enrollment or after discontinuation
Signed consent form with date, CTMS enrollment record
Procedure necessity documentation
What they want
Medical record showing clinical necessity for routine-classified procedures
Procedure only exists in protocol, no clinical documentation
Progress note or order referencing clinical indication separate from protocol
Audit Response Best Practices
Respond within deadline—always
MAC deadlines are typically 45 days. Missing the deadline often results in automatic adverse determination. If you need more time, request an extension in writing before the deadline expires.
Provide exactly what was requested
Don't over-document. If they ask for the MCA, provide the MCA. Don't send the entire protocol, budget, and consent unless specifically requested. Extra documents create extra questions.
Version control is critical
Every document should clearly indicate its version and effective dates. Auditors are trained to spot version mismatches. Your MCA from January should reference the protocol version effective in January—not the current version.
Document your rationale, not just your conclusion
"Routine" is not sufficient. Your documentation should show: "CT Chest classified as routine per NCD 310.1 section X, consistent with standard of care for lung cancer staging. Protocol Section 5.2 specifies CT Chest at 12-week intervals, consistent with NCCN guidelines."
Sample Response Letter Format
[Institution Letterhead]
[Date]
Medicare Administrative Contractor
[Address]
Re: Additional Documentation Request - [Audit Reference Number]
Patient: [Name/HIC]
Dates of Service: [Range]
Dear Review Team,
In response to your request dated [Date], please find enclosed the following documentation supporting Medicare coverage for the services in question:
- Medicare Coverage Analysis (MCA) - Page X provides the coverage determination for each procedure, with NCD 310.1 rationale documented.
- Protocol Version [X], effective [Date Range] - See Section [Y] for procedure schedule supporting coverage determination.
- Budget effective [Date] - Demonstrates cost allocation between routine (Medicare) and research (sponsor) items.
Please contact [Name] at [Phone/Email] if additional information is required.
Respectfully submitted,
[Name, Title]
[Institution]
Building an Audit-Ready Culture
Prospective documentation
Don't create documentation in response to audits—create it as part of your standard workflow. Every MCA should be audit-ready the day it's completed. Every amendment should be documented when processed, not months later.
Regular self-audits
Quarterly, pull a random sample of 10-20 claims billed as routine. Verify each has: (1) complete MCA with rationale, (2) protocol version match, (3) enrollment verification, (4) clinical documentation. Fix gaps before the MAC finds them.
Training and calibration
Annually, review MCA determinations across analysts for consistency. Use de-identified audit findings from peer institutions as training cases. Keep your team calibrated on current MAC expectations.
Build audit-ready documentation automatically
Engram Clinical generates MCA documentation with NCD rationale, version tracking, and audit trails built in. When the MAC calls, you're ready.