GP modifier: Services delivered under an outpatient physical therapy plan of care
Category: Modifier
By Dr. Daniel Turner, DC · Reviewed September 2, 2026
What is GP modifier used for?
The therapy discipline modifier identifying a service as furnished under a physical therapy plan of care. It is one of three discipline modifiers, alongside GO for occupational and GN for speech therapy, and many payers require it on the therapy codes chiropractors bill.
How it works in a chiropractic practice
A modifier chiropractors inherit from therapy billing rules: payers that apply therapy policies to 97110, 97112, 97140, and their siblings often require GP on those lines even when a DC performs the service. The requirement is payer specific and quietly enforced, which makes it a classic source of CO-16 style denials that read as mysterious until the remark code names the missing modifier.
What the note must show
- ✓Applied per payer rule to the therapy service lines, not to CMT or E/M codes
- ✓The underlying plan of care documentation: measurable goals, planned frequency and duration, and progress against them
- ✓Payer rules on file, since some commercial plans require GP where others reject it
A worked example
A commercial payer starts denying 97110 lines with a remark about a missing therapy modifier. The fix is GP on the therapy lines for that payer going forward, and corrected claims for the denied batch. The same practice sends claims to a second payer that wants no modifier at all; per payer rules, not habits, are what keep both clean.
Does Medicare pay chiropractors for GP modifier?
Largely moot for chiropractic Medicare claims since the therapy codes are statutorily excluded, but the modifier matters on the commercial and personal injury claims where those codes actually pay.
Where practices get burned
Blanket GP on every line including CMT; missing it for the payers that require it; treating one payer’s rule as universal.
How Cervica helps with GP modifier
Cervica's claim scrubber validates modifiers, units, and diagnosis pointers for GP modifier before submission, per payer rules handle code substitutions and modifier requirements automatically, and when a payer pushes back anyway the denial worklist reads the adjustment codes and routes the claim to the exact fix.
Related codes
- →97110 · Therapeutic exercise
- →97140 · Manual therapy techniques
- →GY modifier · Statutorily excluded service
- →CO-16 · the denial this code most often triggers
- →CO-4 · the denial this code most often triggers
Quick answers
What is GP modifier used for?
The therapy discipline modifier identifying a service as furnished under a physical therapy plan of care. It is one of three discipline modifiers, alongside GO for occupational and GN for speech therapy, and many payers require it on the therapy codes chiropractors bill.
What documentation does GP modifier require?
Applied per payer rule to the therapy service lines, not to CMT or E/M codes The underlying plan of care documentation: measurable goals, planned frequency and duration, and progress against them Payer rules on file, since some commercial plans require GP where others reject it
Does Medicare pay chiropractors for GP modifier?
Largely moot for chiropractic Medicare claims since the therapy codes are statutorily excluded, but the modifier matters on the commercial and personal injury claims where those codes actually pay.
References
General information for billing teams, not legal, coding, or payer specific advice. CPT is a registered trademark of the American Medical Association; code descriptions here are paraphrased in our own words and the AMA's CPT publications control. Payer policies vary and control for any individual claim.