I don't happen to agree... if a child comes in for a sick visit and the Doctor sees that it is also time to update a vaccine (lets say Dtap or Hep A) we don't add modifier 25 so why would we add it for Flu? It's still just a vaccine. I guess there may be a commercial carrier that requires it or perhaps a state Medicaid program but I bill most of the major commercial carriers (UHC, BCBS [North Carolina], Aetna, Cigna, Medcost) and none of them deny payment on the office visit if it has it's own diagnosis attached.we modify the office visit if the patient has one, and also has a flu shot. The E/M significant, separately identifiable from the "added" flu shot. If they're coming in for flu shot only - then there isn't an E/M (or a need for a modifier then).