Modifier -GO: Services Delivered Under an Outpatient Occupational Therapy Plan of Care

Quick reference

What it signals: -GO is a HCPCS Level II informational modifier that identifies a service as rendered under an outpatient occupational therapy (OT) plan of care.
Mandatory for Medicare Part B OT claims: CMS requires -GO on all Medicare Part B outpatient OT claims. A missing -GO on a Medicare OT claim = automatic denial.
Informational, not reductive: -GO does not trigger any payment reduction on its own. It purely identifies the therapy discipline.
Therapy discipline 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 plan of care under which the service is rendered.

Required on all Part B OT outpatient claims: Every covered OT service billed to Medicare in the outpatient setting must carry -GO, regardless of the setting (private practice, hospital outpatient, SNF Part B, telehealth).
Plan of care requirement: -GO implies an established OT plan of care (POC) is on file, certified by the treating physician or NPP. The POC must be reviewed and recertified at least every 90 days.
Companion modifier -CO: When an OT service is furnished in whole or in part by an Occupational Therapist Assistant (OTA), -CO must also be appended — and a 15% Medicare payment reduction is applied. -GO and -CO stack on the same line when applicable.
KX modifier pairing: When OT charges exceed the CY 2026 Medicare annual therapy threshold of $2,480 (OT has its own separate bucket — does not share with PT/SLP), -KX must also be appended on the over-threshold line.
Commercial payers: AOTA notes that many payers (UHC, Humana, BCBS) also require -GO for OT claims. Confirm payer-specific policy — some require it, some treat it as informational, some don’t require it at all.

Active OT plan of care on file: Signed, dated, physician/NPP-certified OT POC must exist. Recertify every 90 days.
OT credential documented: The treating provider must be a licensed/registered OT (OTR/L) or an OTA operating under appropriate supervision per state law.
Functional goals and medical necessity: Progress notes must document the patient’s functional deficits (ADLs, IADLs, cognitive/motor performance) and measurable, time-bound treatment goals.
Telehealth pairing: For synchronous audio-video OT telehealth billed to Medicare, stack -GO with -95; for audio-only, stack with -FQ.

OT evaluation (low complexity): 97165 — initial OT evaluation, low complexity; requires -GO.
OT evaluation (moderate complexity): 97166 with -GO.
OT evaluation (high complexity): 97167 with -GO.
OT re-evaluation: 97168 with -GO.
Therapeutic activities: 97530 with -GO — one of the most common OT treatment codes.
Therapeutic exercise: 97110 with -GO.
Self-care/home management training: 97535 with -GO — ADL training, a core OT intervention.
Neuromuscular reeducation: 97112 with -GO.
Manual therapy: 97140 with -GO.
Sensory integrative techniques: 97533 with -GO.
Cognitive Skills Training: 97129 (first 15 min) and 97130 (each additional 15 min) with -GO when billed under OT POC.

Date	CPT	Modifiers	Note
MM/DD/YYYY	97165	-GO	OT eval, low complexity, Medicare
MM/DD/YYYY	97530	-GO	Therapeutic activities, OT POC
MM/DD/YYYY	97530	-GO -CO	Therapeutic activities, furnished by OTA; 15% reduction applies
MM/DD/YYYY	97110	-GO -KX	Therapeutic exercise, over $2,480 OT threshold for CY 2026
MM/DD/YYYY	97535	-GO -95	Self-care/ADL training via synchronous video telehealth

Medicare: Mandatory on every outpatient OT claim line. OT threshold is $2,480 for CY 2026 (separate from the PT/SLP combined bucket).
Wisconsin Medicaid: Verify ForwardHealth OT modifier requirements — may differ from Medicare.
Commercial (UHC, BCBS, Aetna, Cigna): Many follow Medicare’s -GO requirement. Check ERA/EOB denial patterns; “missing modifier” denials on OT claims often indicate -GO is expected by that payer.

Is this an outpatient OT service billed under an occupational therapy plan of care?
Is there a current, certified OT plan of care on file?
Is -GO on every OT claim line on the claim?
If an OTA furnished the service (whole or in part), is -CO also on the line?
If OT charges for the year have exceeded $2,480, is -KX also appended?