What MAO-004 is

The MAO-004, formally the Encounter Data Diagnosis Filtering Report, is the file CMS returns to each Medicare Advantage Organization (MAO) every month after it processes submitted encounter data. For each encounter, it lists the diagnoses CMS accepted as eligible for risk adjustment and the diagnoses it filtered out, with a reason code attached to every rejection.

It sits at a specific point in the submission lifecycle. Encounters flow into the CMS Encounter Data System (EDS). The 277CA acknowledgment confirms whether an encounter was accepted into the EDS at all. The MAO-004 sits downstream of the 277CA and answers the next question: of the diagnoses on accepted encounters, which are eligible to flow into a member's risk score. An encounter can clear the 277CA cleanly and still have individual diagnoses filtered on the MAO-004.

Why MAO-004 matters

The MAO-004 is the closest plans get to a near-real-time signal that their documentation is, or is not, holding up for payment. Every diagnosis it rejects is revenue that will not appear in the member's risk score, and revenue does not get recovered unless a corrected diagnosis is resubmitted inside the CMS sweep window.

It is also a forward-looking risk signal. A diagnosis rejected on the MAO-004 is an early warning that the Hierarchical Condition Category (HCC) behind it will not survive a Risk Adjustment Data Validation (RADV) audit either. The same data, linkage, or documentation weakness that triggered the filter is the weakness an auditor will find. Reading and acting on MAO-004 reject reason codes is one of the highest-leverage and most overlooked tasks for a risk adjustment team, because catching a soft HCC at the MAO-004 stage costs far less than defending it after a RADV finding.

How MAO-004 is used

The report is generated on a monthly cadence per contract. A risk adjustment team uses it as a reconciliation and triage instrument, not just an archive file. The working pattern is:

  • Reconcile every monthly file against submitted encounters. Match what you sent to what CMS accepted and filtered, so you know your true recognized diagnosis set rather than your submitted set.
  • Group rejections by reason code. The reason code tells you whether the cause is a data or formatting problem, an ineligible encounter or provider type, a duplicate, or a diagnosis that simply does not map to an HCC.
  • Roll rejections up by provider and source system. A reason code that clusters on one EHR feed or one practice points to a systemic fix, not a one-off correction.
  • Resubmit correctable diagnoses inside the sweep window. A rejection is only recoverable while the submission window for that payment year is open.

Common mistakes teams make with MAO-004

  • Treating the 277CA as the finish line. Teams that stop reconciling once an encounter is accepted into the EDS never see the diagnoses filtered downstream on the MAO-004.
  • Reading the file only at year-end. By the time an annual true-up runs, the sweep window for correcting and resubmitting many of the rejections has closed.
  • Ignoring the reason codes. Counting rejections without grouping by reason code hides the systemic causes that, once fixed, prevent the next month's rejections.
  • Reconciling on submitted RAF instead of recognized RAF. Submitted diagnoses overstate the risk score; only the MAO-004-accepted set reflects what CMS will actually pay on.
  • Not closing the loop to documentation. Each filtered diagnosis is a signal about a chart that is likely thin for RADV, and teams that do not route that signal back to coding lose the audit-defense benefit.

How Pelica handles MAO-004

Pelica's Risk Adjustment Copilot tracks every submitted diagnosis through the full lifecycle, from the 277CA acknowledgment through the MAO-004 and onward to the MMR and MOR, in one record. Reject reason codes are grouped, rolled up by provider and source system, and tied back to the underlying chart so a team can fix the systemic cause and resubmit inside the window. Across Pelica deployments, customers have lifted RAF by roughly +0.4 in two quarters with no new headcount.

Related terms

  • MMR (Monthly Membership Report): the CMS file that reports per-member payment and the risk scores CMS is paying on.
  • MOR (Model Output Report): the report that details the HCCs and risk-score components CMS recognized for each member.
  • 277CA: the claim acknowledgment that confirms whether an encounter was accepted into the Encounter Data System, upstream of the MAO-004.

Sources