| A1 | Dressing for one wound |
| A2 | Dressing for two wounds |
| A3 | Dressing for three wounds |
| A4 | Dressing for four wounds |
| A5 | Dressing for five wounds |
| A6 | Dressing for six wounds |
| A7 | Dressing for seven wounds |
| A8 | Dressing for eight wounds |
| A9 | Dressing for nine or more wounds |
| AA | Anesthesia services performed personally by anesthesiologist |
| AB | Audiology service furnished personally by an audiologist without a physician/npp order for non-acute hearing assessment unrelated to disequilibrium, or hearing aids, or examinations for the purpose of prescribing, fitting, or changing hearing aids; service may be performed once every 12 months, per beneficiary |
| AD | Medical supervision by a physician: more than four concurrent anesthesia procedures |
| AE | Registered dietician |
| AF | Specialty physician |
| AG | Primary physician |
| AH | Clinical psychologist |
| AI | Principal physician of record |
| AJ | Clinical social worker |
| AK | Non participating physician |
| AM | Physician, team member service |
| AO | Alternate payment method declined by provider of service |
| AP | Determination of refractive state was not performed in the course of diagnostic ophthalmological examination |
| AQ | Physician providing a service in an unlisted health professional shortage area (hpsa) |
| AR | Physician provider services in a physician scarcity area |
| AS | Physician assistant, nurse practitioner, or clinical nurse specialist services for assistant at surgery |
| AT | Acute treatment (this modifier should be used when reporting service 98940, 98941, 98942) |
| AU | Item furnished in conjunction with a urological, ostomy, or tracheostomy supply |
| AV | Item furnished in conjunction with a prosthetic device, prosthetic or orthotic |
| AW | Item furnished in conjunction with a surgical dressing |
| AX | Item furnished in conjunction with dialysis services |
| AY | Item or service furnished to an esrd patient that is not for the treatment of esrd |
| AZ | Physician providing a service in a dental health professional shortage area for the purpose of an electronic health record incentive payment |
