MUE stands for Medically Unlikely Edit. It is the maximum number of units Medicare will pay for a CPT/HCPCS code for a single patient on a single date of service. MUEs prevent:
Example: If the MUE for a code is 1 and a provider bills 3 units, Medicare will pay only 1 and deny the rest as “Units exceed MUE.”
For coders and AR teams, understanding MUEs helps prevent denials and ensures claims are billed with correct unit structure.
MAI stands for MUE Adjudication Indicator. MAI tells Medicare how strictly an MUE is enforced and whether an appeal is possible.
There are three MAI categories used for MUE edits:
These limits are based on clinical judgment, policy, or data. If extra units are medically justified, appeals may be successful.
Example: CPT 96372 – Injection (MUE 4). If documentation shows 4 injections were given, excess denied units can be appealed.
These are strict limits. Medicare considers it impossible to bill more than the allowed units. No appeal will overturn this denial.
Example: CPT 45378 – Colonoscopy (MUE 1). You cannot bill more than 1 colonoscopy per day.
These limits are strict but may have rare exceptions. Appeals are possible if strong medical necessity is documented.
Example: CPT 97110 – Therapeutic Exercise (MUE 6). A long post-surgical session might justify extra units.
| MAI Type | Meaning | Appeal Possible? | Strictness |
|---|---|---|---|
| MAI 1 | Claim-level, based on data or clinical judgment | ✅ Yes | Medium strict |
| MAI 2 | Absolute limit — never exceeded | ❌ No | Very strict |
| MAI 3 | Clinical limit, rare exceptions possible | ⚠ Sometimes | Strict but appealable |
AR teams save time by understanding which MUE denials can be corrected and which should not be appealed.
MUEs define the maximum payable units per day, and MAI tells how strictly these limits are enforced. Understanding MUE + MAI improves billing accuracy, prevents unnecessary denials, and guides AR teams on when appeals are worth pursuing.