Glossary · Updated Jul 6, 2026
MUE (Medically Unlikely Edit)
A Medically Unlikely Edit (MUE) is the maximum number of units of a HCPCS/CPT code that CMS considers plausible for one patient on one date of service. It is a claims-editing threshold meant to catch clear billing errors — not a statement of the correct or typical number of units.
What the value catches
An MUE value guards against gross errors like a misplaced decimal, a per-unit code billed as a per-encounter count, or a data-entry mistake — not against clinically implausible-but-real high-unit claims, which is why exceeding the value does not automatically mean the billing was wrong.
The adjudication indicator
How an excess is handled depends on the MUE adjudication indicator (MAI). An MAI of 1 is a claim-line edit: units above the limit on a single line are denied, and the line can be resubmitted correctly. An MAI of 2 is a date-of-service edit: units are summed across all lines for that code on that date before the limit is checked. An MAI of 3 is a clinical edit: still checked per date of service, but the denial can be appealed with supporting documentation, unlike 1 or 2.
| MAI | Edit type | How excess units are handled |
|---|---|---|
| 1 | Claim-line edit | Units above the limit on a single line are denied; the line can be resubmitted correctly |
| 2 | Date-of-service edit | Units are summed across all lines for that code on that date before the limit is checked |
| 3 | Date-of-service edit, clinical | Checked per date of service, but the denial can be appealed with supporting documentation |
A ceiling, not a target
A code without a published MUE simply has no unit limit from this particular edit — it is not evidence that unlimited units are appropriate. Likewise, billing right up to the MUE limit is not itself a signal of correct coding; the limit only screens out clearly implausible unit counts.
Frequently asked
Does exceeding the MUE always deny the claim?
It depends on the adjudication indicator. Claim-line (1) and date-of-service (2) edits deny the excess units outright; a clinical (3) edit can be appealed with documentation.
Is there an MUE for every code?
No. Codes without a published MUE are not limited by this edit, though other edits (like PTP) may still apply.
Related
Sources
Written from primary CMS sources — see how we source, compute, and verify everything on this site.