Remittance Advice · Payment-time (remittance)
OHIP explanatory code HM
Invalid master number used on date of service
What HM means
The Ministry of Health’s official wording for HM is: “Invalid master number used on date of service.”
This code appears as an explanatory code on your monthly Remittance Advice (RA). It means the claim was adjudicated — paid, reduced, or refused — for the reason below. A claim already on your RA generally shouldn't be blindly resubmitted; follow the suggested action.
How to fix HM
This explains a payment adjustment. If you believe the claim was billed correctly, file a Remittance Advice Inquiry within the deadline; otherwise no resubmission is needed.
Payment-time codes appear on the monthly Remittance Advice after adjudication. Some are informational, some explain a reduced or refused payment. Where you disagree with the outcome, the usual route is a Remittance Advice Inquiry or written inquiry — not resubmitting the same claim, which can create a duplicate.
Related codes
- H9Concurrent care already claimed by another doctor
- HAAdmission assessment claimed by another physician-hospital visit fee applied
- HBSubsequent Visit Already Paid Same Day
- HFConcurrent or supportive care already claimed in period
- I2Service is globally funded
- I3Fee Schedule Code is not on the IHF (Independent Health Facility) licence profile for the date specified
- I4Records show service has been rendered by another Practitioner, Group or IHF
- I5Service is globally funded and Fee Schedule Code is not on IHF licence profile
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Code meaning per Ontario Ministry of Health — Remittance Advice Explanatory Codes / Messages (March 2026). The suggested action is general information for Ontario physicians, not billing, legal, or tax advice — codes and rules change, so verify against the current Ministry of Health documents before relying on a claim.