Modifier -GN: Services Delivered Under an Outpatient Speech-Language Pathology Plan of Care

Quick reference

What it signals: -GN is a HCPCS Level II informational modifier that tells the payer the service was rendered under an outpatient speech-language pathology (SLP) plan of care.
Mandatory for Medicare Part B SLP claims: CMS requires -GN on all Medicare Part B outpatient SLP claims. A missing -GN on a Medicare SLP claim = automatic denial.
Informational, not reductive: Unlike -CQ, -GN is purely informational — it does not trigger a payment reduction. It identifies the therapy discipline.
Discipline identification trio: Medicare uses three therapy discipline modifiers: -GN (SLP), -GP (PT), -GO (OT). Only one discipline modifier is appended per claim line based on the therapy plan under which the service is rendered.

Required on all Part B SLP outpatient claims: Every covered SLP service billed to Medicare in the outpatient setting must carry -GN. There are no exceptions for this requirement.
Applies regardless of setting: Whether the SLP service is rendered in a private practice, hospital outpatient department, SNF Part B, or via telehealth — -GN is required on all Medicare outpatient SLP claims.
Plan of care requirement: The -GN modifier implies an established SLP plan of care (POC) exists. Medicare requires that the POC be established by a qualified SLP and certified by the treating physician/NPP.
Commercial payers: Many commercial payers (UHC, BCBS, Aetna, Cigna) have adopted -GN as well, though policies vary. Check payer-specific guidelines — some require it, some consider it informational, some do not require it at all.
KX modifier pairing: When SLP charges exceed the Medicare annual therapy threshold ($2,410 for 2025), -KX must also be appended on the over-threshold line to indicate continued medical necessity. -GN and -KX can stack on the same line.

Active SLP plan of care on file: There must be a signed, dated, physician-certified SLP plan of care. The POC must be updated at least every 90 days (or per certification period).
SLP credential documented: Confirm the treating provider is a licensed/certified SLP (CCC-SLP) or a CF/SLPA under appropriate supervision as allowed by state law.
Medical necessity supported: Progress notes must document the patient’s functional communication, swallowing, or cognitive-communication deficits and measurable treatment goals.
Telehealth pairing: If the SLP session is conducted via synchronous audio-video telehealth, bill with both -GN and -95 (for Medicare).

Speech/language/voice treatment (individual): 92507 — the most frequently billed SLP treatment code; requires -GN on every Medicare line.
Swallowing therapy: 92526 with -GN.
Speech evaluation: 92521 (fluency), 92522 (sound production), 92523 (language comprehension/expression), 92524 (voice analysis) — all require -GN for Medicare.
Cognitive-linguistic therapy: 97129 (therapeutic interventions for cognitive function, 1st 15 min) and 97130 (each additional 15 min) with -GN.
AAC device training: 92609 (use of speech generating device) with -GN.
Auditory rehabilitation: 92630, 92633 with -GN when billed under SLP POC.

Date	CPT	Modifiers	Note
MM/DD/YYYY	92507	-GN	Individual SLP treatment, Medicare
MM/DD/YYYY	92507	-GN -95	SLP treatment via synchronous video telehealth
MM/DD/YYYY	92507	-GN -KX	SLP treatment exceeding annual therapy cap threshold
MM/DD/YYYY	92526	-GN	Swallowing therapy, Medicare

Medicare: Mandatory on every outpatient SLP claim line. No -GN = denial.
Wisconsin Medicaid: Verify current ForwardHealth guidance; SLP modifier requirements may differ from Medicare.
Commercial (UHC, BCBS, Aetna, Cigna): Many follow Medicare’s -GN requirement for SLP. Check ERA/EOB denial patterns — if you see “missing modifier” denials on SLP claims, -GN is often the culprit.

Is this an outpatient SLP service billed under a speech-language pathology plan of care?
Is there a current, certified SLP plan of care on file?
Is -GN on every SLP claim line (not just one line on a multi-line claim)?
If charges exceed the therapy cap threshold, is -KX also appended?
If telehealth, is -95 (audio-video) or -FQ (audio-only Medicare) also stacked with -GN?