Modifier -CQ: PT Services Furnished In Whole or In Part by a Physical Therapist Assistant

Quick reference

What it signals: -CQ identifies that a physical therapy service was furnished in whole or in part by a Physical Therapist Assistant (PTA) — not the supervising Physical Therapist (PT).
Mandatory for Medicare Part B: Effective January 1, 2020, CMS requires -CQ on any PT claim line where a PTA participated in furnishing that service. Failure to append it is a compliance violation.
15% payment reduction triggered: Appending -CQ to a CPT line automatically triggers a 15% reduction in Medicare reimbursement for that specific line. The reduction applies line-by-line, not claim-wide.
Companion modifier -CO: -CO is the equivalent modifier for Occupational Therapist Assistants (OTAs); -CQ is PT only.

“In whole or in part” standard: If a PTA furnishes any portion of the service on that line, -CQ is required — unless the de minimis exception applies (see below).
De minimis / ≥8-minute rule exception: If the supervising PT personally furnishes ≥8 minutes of the last billable unit of a timed service, that unit may be billed without -CQ, even if the PTA participated in earlier units on the same date. CMS confirmed this in the CY 2022 Physician Fee Schedule Final Rule.
Paired with therapy discipline modifier: -CQ is always used in addition to — not instead of — the -GP modifier (physical therapy plan of care). The line will carry both -GP and -CQ.
Untimed codes: -CQ applies to untimed procedure codes as well when a PTA furnished the service in whole.
Joint treatment: If the PT and PTA provide the full treatment together for the entire session, -CQ is not applied — the service is considered provided by the PT.

Identify who performed each unit: Therapy notes must clearly document which clinician (PT vs. PTA) performed each timed unit. This is critical for the de minimis analysis.
Total time per clinician: Record both PT and PTA minutes per CPT code on each date of service.
Plan of care: The supervising PT must have an established, active plan of care (-GP) on file. The PTA operates under this plan.
Supervision level documented: Document that the required level of supervision (direct or general, per setting) was maintained.

Therapeutic exercise: 97110 (Therapeutic exercises) — most frequently billed PT code with -CQ.
Therapeutic activities: 97530 (Therapeutic activities) with -CQ.
Neuromuscular reeducation: 97112 with -CQ.
Gait training: 97116 with -CQ.
Manual therapy: 97140 with -CQ.
Self-care/home management: 97535 with -CQ.
Aquatic therapy: 97113 with -CQ.
All of the above also carry -GP on the same line.

Date	CPT	Modifiers	Units	Note
MM/DD/YYYY	97110	-GP -CQ	2	PTA performed; 15% reduction applies
MM/DD/YYYY	97530	-GP	1	PT personally performed ≥8 min last unit; no CQ

Medicare: -CQ is mandatory; missing modifier = compliance risk and potential overpayment. 15% reduction is applied per line.
Commercial payers (BCBS, UHC, Aetna, Cigna): Not all commercial payers require -CQ or apply the 15% reduction — verify individual payer contracts. Many follow Medicare but some do not have a PTA differential.
Medicaid: Varies by state. Confirm your state Medicaid fee schedule for PTA differential policies.

Did a PTA furnish the service in whole or in part (and the de minimis exception does not apply)?
Is -GP also on the same claim line?
Is there documentation of PT minutes vs. PTA minutes per timed unit to support the de minimis analysis?
Is this a Medicare or payer that requires -CQ?