What the CQ modifier indicates
CQ identifies applicable Medicare outpatient physical therapy services furnished in whole or in part by a physical therapist assistant (PTA). When required, CMS instructs providers to report CQ with the GP therapy modifier on the claim line for the service. The modifier is not a default for every visit involving a PTA.
Check the service-level threshold and exceptions
CMS’s general de minimis standard applies when the PTA independently furnishes more than 10% of a service or unit. Whether CQ applies depends on who furnished the service, the code and unit being billed, and how the minutes are allocated. CMS also describes exceptions, including specific situations involving the final 15-minute unit when the PT or OT independently meets the 8-minute threshold.
Do not apply the 10% figure mechanically to total visit minutes or assume that any PTA involvement means every billed unit needs CQ. Review the current CMS therapy-services guidance and its CQ/CO billing examples for the date of service and service-specific details.
What to verify before a claim is submitted
Confirm the applicable payment setting, service date, code, unit, who furnished the service, documented minutes, and whether the exception rules change the result. Check the required GP pairing and claim-line reporting. The 2026 annual therapy code list also identifies code-specific scope for certain therapy-related services; do not assume the same threshold applies to every code.
If the documentation does not establish who furnished the service or how time was allocated, resolve that first. This is a general Medicare explainer, not individualized coding advice. Keep commercial payer requirements separate from CMS rules.