MFN^M04 — Master File Notification — Charge Description Master

The message that synchronises the billable code catalogue (Charge Description Master, CDM) between billing systems, the HIS and the pharmacy. The core of a facility's pricing reference.

Purpose

The Charge Description Master (CDM) is the reference catalogue of a facility's billable codes: each procedure, session, device, dispensable drug appears with its code (internal, CPT, HCPCS, NDC), its label and its tariff. When the CDM evolves (code added, tariff updated, code retired), M04 propagates the change to every system that consumes the CDM.

Typical cases: addition of a new CPT after AMA's October publication, annual tariff update, addition of a dispensable drug, retirement of an obsolete procedure. In the US, the CDM is central for Medicare, Medicaid and commercial payers.

Segment structure

MFN_M04
  MSH                    Message Header
  MFI                    Master File Identification
  { MFE                  Master File Entry (1..*)
    CDM                  Charge Description Master segment
    [ { PRC } ]          Pricing segment (1..*)
  }

MFE-1 Record-Level Event Code:

• MAD — Add record
• MUP — Update record
• MDL — Delete record
• MAC — Activate record
• MDC — De-activate record

Real-world example

Update of CPT 99213 tariff to 150 USD, effective 01/06/2026:

MSH|^~\&|BILLING|HOSP01|HIS|HOSP01|20260516160000||MFN^M04^MFN_M04|MSG-MFN-M04-2026-09|P|2.5.1|||AL|NE
MFI|CDM^Charge Description Master^HL70175|||UPD|20260516160000|AL
MFE|MUP|||CDM-99213|20260601000000
CDM|99213^Office visit, est patient, expanded^CPT|H99213|Office visit, established patient (15 min)|||150.00
PRC|99213^Office visit, est patient, expanded^CPT|CDM-99213||O|150.00|150.00|U|150.00

• MFI-1 = CDM (master file type).
• MFI-3 = UPD (update mode).
• MFE-1 = MUP (update record).
• MFE-4 = CDM-99213 (primary key in the CDM).
• MFE-5 = effective date 20260601000000.
• CDM-2 = H99213 (internal facility code).
• CDM-6 = tariff 150.00.
• PRC = price line (Charge, Override, Routine), 150 USD.

Acknowledgment (ACK / MFK)

Master files use a specific acknowledgment MFK (instead of the standard ACK), which includes an MFA segment recording acceptance granularity at each record level:

MSH|^~\&|HIS|HOSP01|BILLING|HOSP01|20260516160001||MFK^M04^MFK_M01|ACK-MFN-M04-2026-09|P|2.5.1
MSA|AA|MSG-MFN-M04-2026-09
MFI|CDM^Charge Description Master^HL70175|||UPD|20260516160000|AL
MFA|MUP|||AA|20260516160000|CDM-99213

Common errors

• Inconsistent MFI-3: must be UPD (update) or REP (replace). UPD = update by key; REP = full replacement.
• MFE without CDM segment: the CDM segment is mandatory in M04. Without CDM, MFE is unusable.
• Tariffs without currency: for multi-country deployments, specify the currency (CDM-7 or PRC-7 Currency).
• Effective date missing: for a tariff change, MFE-5 must always be populated to allow correct billing.
• No MFK received: unlike a plain ACK, MFK confirms application; without MFK, the sender cannot guarantee synchronisation.

Related messages

See also: MFN^M01 — generic master file and DFT^P10 — billing.