What is the 8-minute rule?

Under Medicare, units of timed therapy codes are based on total timed minutes in the session: for example, 8 to 22 minutes supports one unit and 23 to 37 minutes supports two. Some commercial payers use different counting methods, so confirm each payer.

What does the KX modifier do?

Medicare applies a therapy threshold; once exceeded, the KX modifier attests that services remain medically necessary and documentation supports it. Verify the current threshold amount.

How much does physical therapy billing cost with Bill For You RCM?

The greater of $650 a month or 2.99% of monthly collections, with $0 setup and no long-term contract. See the pricing page.

Physical Therapy Billing Services

Bill For You RCM manages billing for physical therapy, occupational therapy and rehab practices: timed-code unit review, modifier use, authorization and visit-limit tracking, claim submission, denial appeals and A/R follow-up. Fee: the greater of $650 a month or 2.99% of collections.

Reviewed October 23, 2026. Codes and payer rules change; confirm against the current CPT code set and each payer’s policy.

Why therapy billing is different

Timed codes: units depend on documented minutes, and payers count them differently.
Plan of care: Medicare requires a certified plan of care and periodic progress reports.
Modifiers: therapy modifiers and payment modifiers affect payment and compliance.
Visit limits and authorizations: many plans cap visits or require authorization.
Multiple payer types: commercial, Medicare, workers’ compensation and auto-injury cases follow different rules.

Common therapy codes and modifiers

Code or modifier	What it is	Billing note
97161-97163, 97164	PT evaluation (low, moderate, high complexity) and re-evaluation	Complexity must be supported by documentation.
97110, 97112, 97140, 97530	Therapeutic exercise, neuromuscular re-education, manual therapy, therapeutic activities	Timed codes: units follow documented minutes.
GP, GO, GN	Services under a PT, OT or speech plan of care	Required by Medicare on therapy claims.
KX	Threshold attestation	Used after the Medicare therapy threshold with supporting documentation.
CQ, CO	Services furnished in whole or part by a PTA or OTA	Medicare pays a reduced percentage for these services.
59 or X modifiers	Distinct procedural service	Used only when edits allow and documentation supports it.

Where therapy claims get denied

Units billed do not match documented minutes.
Missing, expired or uncertified plan of care, or overdue progress reports.
Visit limit reached or authorization not on file.
Missing or incorrect therapy or PTA/OTA modifiers.
Direct-access and referral rules that differ by state and payer.
Timely filing missed on workers’ compensation or auto claims.

What we handle

Timed-code and unit review against documentation.
Eligibility, benefits and visit-limit checks; authorization tracking.
Claim submission, payment posting and denial appeals.
Aged A/R recovery and monthly reports on denials and A/R.
Credentialing for new therapists. Learn more.