X12 837P SV103 (Unit or Basis for Measurement Code): Format, Values, and Testing Notes
SV103 sets the ruler that SV104 gets measured against — pick minutes when the payer expects units, or vice versa, and the count in SV104 gets interpreted completely differently than the biller intended.
SV103 is the Unit or Basis for Measurement Code in an X12 837P service line — it tells the reader what SV104's count actually counts. On professional claims it's almost always UN (units), with MJ (minutes) showing up for time-based services like anesthesia or therapy.
Valid code values
Example
UN tells the reader that the 1 in SV104 means one unit of the procedure, not one minute. Synthetic claim data.
Where this trips people up
Anesthesia and time-based therapy billing are the two spots teams most often get SV103 wrong in test data, because the same line can plausibly be expressed in either units or minutes depending on the biller's system of record — and a generator that defaults every line to UN regardless of procedure type never produces the MJ scenario that payer-specific anesthesia pricing logic actually needs to be tested against.