CPT & HCPCS Modifiers

A category-organized, searchable reference to the most-billed CPT (Level I) and HCPCS Level II modifiers. Each modifier has its own page. Search a code (e.g., 25, 59, LT) or a keyword.

How modifiers work

A modifier is a two-character code appended to a CPT/HCPCS code that adds detail without changing its meaning. Pricing modifiers (50, 51, 52, 53, 62, 66, 80/81/82/AS, 26, TC, anesthesia AA/QK/QX/QY/QZ) change the allowed amount and must be sequenced before informational ones. CPT modifiers are numeric (AMA); HCPCS Level II are alpha/alphanumeric (CMS).

Highest denial risk: 25, 59 (and X{EPSU}), 24, 57, 76/77, and 26/TC are repeat OIG audit targets — use only with supporting documentation.

Reference only — CPT descriptors are AMA-copyrighted and paraphrased here. Payer rules and payment percentages vary; verify against the current CPT codebook (Appendix A), the CMS HCPCS Level II file, and payer policy.

CPT numeric modifiers (AMA · CPT Appendix A)

22 — Increased Procedural Services — work substantially greater than typical. Requires documentation of the extra intensity/time/difficulty; supports an above-fee-schedule payment request. Not for E/M.

23 — Unusual Anesthesia — general anesthesia used where the procedure usually needs none or only local/regional. Anesthesia codes only.

24high-risk — Unrelated E/M During a Postoperative Period — same physician provides an E/M unrelated to the original surgery during its global period. Must link a clearly unrelated diagnosis.

25high-risk — Significant, Separately Identifiable E/M on the Same Day as a Procedure — E/M above and beyond the usual pre/post work of a same-day procedure. The single highest-misuse modifier; documentation must establish a service distinct from the procedure's inherent work.

26high-risk — Professional Component — bills only the physician's interpretation/supervision portion of a split (PC/TC) service. Valid only on PC/TC indicator '1' codes; the PC share varies by code per MPFS RVUs.

27 — Multiple Outpatient Hospital E/M Encounters on the Same Date — facility (hospital outpatient) use.

32 — Mandated Services — service required by a third party (e.g., a payer-mandated second opinion).

33 — Preventive Services — flags an ACA-designated preventive service so commercial payers waive cost-sharing. PT is the Medicare counterpart.

47 — Anesthesia by Surgeon — surgeon personally provided regional/general anesthesia. Not added to anesthesia codes; many payers give no extra payment.

50 — Bilateral Procedure — same procedure on both sides, same session. Typically pays 150% of the unilateral allowance. Report as one line/one unit. Not for codes already described as bilateral.

51 — Multiple Procedures — multiple procedures, same session, same provider. Triggers the multiple-procedure reduction (100%/50%/50%…). Not for add-on or 51-exempt codes.

52 — Reduced Services — service partially reduced or eliminated at provider discretion. Payment reduced.

53 — Discontinued Procedure — provider terminates a started procedure due to patient risk. Medicare commonly pays ~half. (ASC/hospital outpatient use 73/74 instead.)

54 — Surgical Care Only — surgeon does the operation; another provider does pre/post care. Paid the intra-operative percentage of the global package.

55 — Postoperative Management Only — provider furnishes only post-op care. Paid the post-op percentage.

56 — Preoperative Management Only — provider furnishes only pre-op care.

57high-risk — Decision for Surgery — E/M that led to the initial decision for a major (90-day global) surgery. Often confused with 25 (minor/same-day procedures).

58 — Staged or Related Procedure During Postoperative Period — planned/staged or more extensive procedure; a new global period begins.

59high-risk — Distinct Procedural Service — non-E/M service distinct from another same-day service (different site/session/lesion). Heavy OIG target; use only when no more specific X modifier fits.

62 — Two Surgeons (Co-Surgeons) — two surgeons each perform distinct parts; each paid 62.5% of the global fee. The MPFS co-surgeon indicator must be 1 or 2.

63 — Procedure on Infant Less Than 4 kg — indicates increased complexity/risk in neonates; supports increased payment. A 63-exempt code list applies.

66 — Surgical Team — more than two surgeons of different specialties. Paid by report; some payers pay 150% split among the team.

73 — Discontinued Outpatient/ASC Procedure Before Anesthesia — facility modifier; typically ~50% facility payment.

74 — Discontinued Outpatient/ASC Procedure After Anesthesia — facility modifier; full facility payment often allowed.

76high-risk — Repeat Procedure by Same Physician — same service repeated the same day by the same provider. Not for E/M.

77high-risk — Repeat Procedure by Another Physician — same service repeated by a different provider.

78 — Unplanned Return to the OR for a Related Procedure During the Postoperative Period — pays the intra-operative portion; does not restart the global period.

80 — Assistant Surgeon — physician assists throughout. Paid 16% of the surgical fee schedule (Medicare).

81 — Minimum Assistant Surgeon — physician provides minimal assistance.

82 — Assistant Surgeon (Qualified Resident Unavailable) — teaching-hospital setting; requires documentation that no qualified resident was available.

90 — Reference (Outside) Laboratory — test sent to and performed by an outside lab but billed by the ordering entity.

91 — Repeat Clinical Diagnostic Laboratory Test — medically necessary repeat of the same lab test, same day, for serial values. Not for re-running an abnormal result.

92 — Alternative Laboratory Platform Testing — test performed with a portable/handheld/kit platform.

93 — Synchronous Telemedicine via Audio-Only — real-time telephone-only service (added 2022). For Medicare audio-only behavioral health, FQ may be required instead.

95 — Synchronous Telemedicine via Audio and Video — real-time interactive audio-video; tied to CPT Appendix P eligible codes; reported with POS 02/10.

96 — Habilitative Services — services to develop skills not previously acquired (effective 1/1/2018; replaced the deleted SZ modifier).

97 — Rehabilitative Services — services to restore previously held skills lost to illness/injury (effective 1/1/2018).

99 — Multiple Modifiers — signals that several modifiers apply to one line.

Anesthesia physical status (P1–P6)

P1 — Normal healthy patient. 0 added units.

P2 — Mild systemic disease. 0 added units.

P3 — Severe systemic disease. Commonly +1 unit (commercial).

P4 — Severe systemic disease that is a constant threat to life. Commonly +2 units.

P5 — Moribund patient not expected to survive without the operation. Commonly +3 units.

P6 — Declared brain-dead patient whose organs are being removed for donation. 0 added units.

Category II performance measurement

1P — Measure not performed for medical reasons.

2P — Measure not performed for patient reasons.

3P — Measure not performed for system reasons.

8P — Measure not performed, reason not otherwise specified.

Anatomical / laterality (HCPCS Level II)

LT — Left side — identifies a procedure on the left of a paired structure.

RT — Right side — identifies a procedure on the right of a paired structure.

E1 — Upper left eyelid.

E2 — Lower left eyelid.

E3 — Upper right eyelid.

E4 — Lower right eyelid.

FA — Left thumb.

F1 — Left index finger.

F2 — Left middle finger.

F3 — Left ring finger.

F4 — Left little finger.

F5 — Right thumb.

F6 — Right index finger.

F7 — Right middle finger.

F8 — Right ring finger.

F9 — Right little finger.

TA — Left great toe.

T1 — Left second toe.

T2 — Left third toe.

T3 — Left fourth toe.

T4 — Left little toe.

T5 — Right great toe.

T6 — Right second toe.

T7 — Right third toe.

T8 — Right fourth toe.

T9 — Right little toe.

LC — Left circumflex coronary artery.

LD — Left anterior descending coronary artery.

LM — Left main coronary artery.

RC — Right coronary artery.

RI — Ramus intermedius coronary artery.

Ambulance arrangement (HCPCS Level II)

QM — Ambulance service provided under arrangement by a provider of services.

QN — Ambulance service furnished directly by a provider of services.

GM — Multiple patients transported on one ambulance trip.

Distinct-service X{EPSU} (replace 59 when one applies)

XEhigh-risk — Separate Encounter — distinct because it occurred during a separate encounter, same day.

XShigh-risk — Separate Structure — distinct because performed on a separate organ/structure.

XPhigh-risk — Separate Practitioner — distinct because performed by a different practitioner.

XUhigh-risk — Unusual Non-Overlapping Service — distinct because it does not overlap the main service's usual components.

Liability / ABN (HCPCS Level II)

GA — Waiver of liability (ABN) on file, required by payer policy — used when a denial is expected for lack of medical necessity; assigns liability to the beneficiary on denial. Don't combine with GX/GY/GZ.

GX — Voluntary ABN issued — for statutorily excluded/non-covered services where an ABN was given voluntarily.

GY — Statutorily excluded / not a Medicare benefit — forces an automatic denial (useful for secondary-payer billing). No ABN needed.

GZ — Expected to be denied as not reasonable/necessary; no ABN obtained — lines auto-deny and the patient is not held liable. Never bill with GA or GY.

Telehealth (HCPCS Level II)

GT — Via interactive audio-video — now mainly for Critical Access Hospital Method II institutional claims; CMS dropped GT for professional claims in 2018.

GQ — Via asynchronous (store-and-forward) telecommunications — historically tied to Alaska/Hawaii demonstrations; some Medicaid use.

FQ — Audio-only communication technology (Medicare behavioral health; FQHC/RHC). Active 2025/2026.

FR — Supervising practitioner present via real-time two-way audio-video (created 2022).

G0 — Telehealth for diagnosis/evaluation/treatment of acute stroke symptoms.

Therapy discipline & assistants

GP — Services delivered under a physical therapy plan of care.

GO — Services delivered under an occupational therapy plan of care.

GN — Services delivered under a speech-language pathology plan of care. (Only one discipline modifier per line — never stack GP/GO/GN.)

CQ — Service furnished in whole or part by a physical therapist assistant (PTA) — triggers 85% of the PT rate; required when a PTA furnishes more than 10% of a service (since 1/1/2020, alongside GP).

CO — Service furnished in whole or part by an occupational therapy assistant (OTA) — 85% payment alongside GO.

KX — Requirements specified in the medical policy have been met — for therapy, attests medical necessity above the annual KX threshold; also used in DMEPOS and CRC screening contexts.

Surgical / provider-role

AS — PA, NP, or CNS as assistant at surgery — must accompany 80/81/82. Medicare pays the assistant-at-surgery rate (16%), and NPP services at 85% of that.

GC — Service partly performed by a resident under a teaching physician (present for key portions).

GE — Resident service under the primary care exception (no teaching physician present).

FS — Split/shared E/M visit (facility settings) — bill under the NPI of the practitioner performing the substantive portion. Not for office/outpatient 99202–99215.

Q5 — Substitute physician under a reciprocal billing arrangement.

Q6 — Substitute physician under a fee-for-time ('locum tenens') arrangement — 60-day continuous limit (active-duty military exception).

Anesthesia provider

AA — Anesthesia personally performed by the anesthesiologist. 100%.

AD — Medical supervision, more than 4 concurrent procedures — reduced/fixed-unit payment (no time units).

QK — Medical direction of 2–4 concurrent procedures. 50%.

QY — Medical direction of one CRNA/AA by an anesthesiologist. 50%.

QX — CRNA/AA service with medical direction. 50%.

QZ — CRNA service without medical direction. 100% (CRNA-specific).

QS — Monitored anesthesia care (MAC) — informational; report actual time and a pricing modifier too.

G8 — MAC for a deep/complex/markedly invasive procedure — informational.

G9 — MAC for a patient with a severe cardiopulmonary history — informational.

Drug modifiers

JW — Drug amount discarded/not administered (single-dose vial/package wastage) — billed on a separate line for the wasted units.

JZ — Zero drug amount discarded — required since 7/1/2023; single-dose drug claims without JW or JZ may be returned as unprocessable for DOS on/after 10/1/2023.

JG — 340B-acquired drug (legacy) — no longer valid for 340B reporting for DOS on/after 1/1/2025.

TB — 340B-acquired drug (informational) — all 340B covered entities must report TB beginning 1/1/2025. No payment reduction.

Medicare-specific / other

PT — Colorectal screening converted to diagnostic/therapeutic — Medicare only; waives the deductible. Coinsurance phasing out (15% 2023–2026, 10% 2027–2029, 0% from 2030).

CR — Catastrophe/Disaster Related — Part B flag during declared emergencies/Section-1135 waivers. Use only during an active declared event.

CS — Cost-sharing waived — a COVID-19 PHE mechanism (FFCRA). Do not use outside an active waiver.

QW — CLIA-waived test — must be first-listed; a valid CLIA certificate number must appear on the claim. No payment change; prevents denials.

GV — Attending physician not employed by or under arrangement with the hospice (related care, Part B, attending only).

GW — Service unrelated to the hospice patient's terminal condition (facility claims use Condition Code 07 instead).

PO — Excepted services at an off-campus provider-based outpatient department (grandfathered; full OPPS rate).

PN — Non-excepted off-campus provider-based department — triggers the lower site-neutral/MPFS-equivalent rate. Don't report PO and PN on the same line.

PA — Surgical 'never event': wrong body part. Non-covered; related lines are reviewed/denied.

PB — Surgical 'never event': wrong patient. Non-covered.

PC — Surgical 'never event': wrong surgery. Non-covered. (Do not confuse with modifier 26, professional component.)

MX — Inpatient 'never event': wrong surgery.

MY — Inpatient 'never event': wrong body part.

MZ — Inpatient 'never event': wrong patient.

SG — ASC facility service (distinguishes facility from professional charge). Largely phased out for Medicare; some commercial payers still reference it.

TChigh-risk — Technical Component — equipment/supplies/technical staff portion of a split service; TC + 26 = the global service. Valid only on PC/TC indicator '1' codes; the split varies by code per MPFS RVUs.

FX — X-ray taken using film — 20% technical-component reduction.

FY — Computed (cassette-based) radiography — 10% technical-component reduction (since CY2023).

CT — CT performed on non-NEMA-XR-29-compliant equipment — 15% reduction.

No modifiers match your search.

Frequently asked questions

What is a modifier in medical billing?

A two-character code appended to a CPT or HCPCS code that adds detail without changing the code's meaning — e.g., that a service was bilateral (50), distinct (59), or telehealth (95). Modifiers affect payment and prevent denials.

What is the difference between CPT and HCPCS modifiers?

CPT (Level I) modifiers are two-digit numeric codes (plus P1–P6 and Category II) maintained by the AMA. HCPCS Level II modifiers are alpha or alphanumeric and maintained by CMS.

Which modifiers cause the most denials?

Modifiers 25 and 59 (and the X{EPSU} set), plus 24, 57, 76/77 and 26/TC, are repeat OIG audit targets. Use them only with documentation that supports a distinct or separately identifiable service.

What is the difference between modifier 25 and 57?

Modifier 25 is for a significant, separate E/M on the same day as a minor procedure. Modifier 57 is for the E/M that led to the decision for a major (90-day global) surgery. Mismatching them against the global period triggers automatic denials.

When should I use an X modifier instead of 59?

Use XE (separate encounter), XS (separate structure), XP (separate practitioner), or XU (unusual non-overlapping) whenever one specifically applies; reserve 59 for when none fits.

Sources: AMA CPT Appendix A; CMS HCPCS Level II file and Medicare Claims Processing Manual; MAC bulletins (Noridian, Palmetto); HHS-OIG. Descriptions paraphrased. Last reviewed June 2026.