Ancillary discounting applies to ancillaries within the same EAPG. With ancillary discounting, the 3M grouper software reads the first ancillary line billed on the claim and assumes that to be the ancillary line paid in full, all other ancillary lines with the same EAPG are then tagged in the grouper and will therefore discount at 50%. (Please note that this does not apply to ancillary services that will package with surgical or medical visit EAPGs.)