Error code
MU — Maximum Units Exceeded
Too many units
More units were billed than the maximum allowed for this fee code.
What to do: Check the code's unit limit and compare the units with the start and stop times in your record.
- Code
- MU
- Description
- Maximum Units Exceeded
Explanation
Updated October 26, 2026
MU means more units were billed than the code allows. Check the code's unit limit and your time records.
What it means
MU means the number of units billed is more than the maximum allowed for the fee code.
Time-based codes are billed in units, and many have a limit per day or per period. For example, case conferences are limited to 8 units per physician per patient per day (Schedule A33). Units also need start and stop times in the chart (GP7).
Common causes
- More units billed than the listing allows
- Units counted on time that isn't consecutive when the code requires consecutive time
How to fix it
- Check the fee code's unit limit in the Schedule of Benefits.
- Check the units against the start and stop times in your record.
- If you believe the decision is wrong, send a Remittance Advice Inquiry (RAI) through eSubmit, or on form 0918-84, within 7 months of the RA date, with supporting details.
Don't resubmit if
- The unit limit was already reached.
- The line is already on your RA. Question it with an RAI, not a new claim.
How APEX handles it
APEX reads your error reports and remittance advice from MCEDT and lists claims rejected with this code in its Correction Centre for you to correct and resubmit. See how APEX works · Pricing
Sources
- Remittance Advice Explanatory Codes/Messages (Ministry of Health, March 2026)
- Schedule of Benefits: Physician Services (July 1, 2026)
- Resource Manual for Physicians: Claims submission (Ministry of Health)
- INFOBulletin 230402: Update, claim submission timeframe for in-province accounts (RAI period now 7 months)