If your clinic employs Physical Therapist Assistants (PTAs), you’re likely already aware that Medicare and other payers don’t treat all services equally when it comes to billing. And if you’ve ever had a claim denied or reimbursed at a lower rate due to a PTA, then you know how important it is to get this right.
The truth is, billing for PT assistants can be confusing—but it doesn’t have to be. Whether you’re new to hiring PTAs or just want to avoid revenue loss due to incorrect billing, this guide will walk you through exactly what you need to know in 2025.
Why PTAs Are Vital—But Tricky to Bill For
PTAs are essential in most physical therapy practices. They allow your licensed PTs to treat more patients and scale your clinic’s capacity. But Medicare and other insurance providers have specific rules on what services PTAs can perform—and how those services are reimbursed.
The kicker? If you don’t follow the billing guidelines exactly, you could be reimbursed less—or not at all.
And in 2025, Medicare’s policies around PTA billing are tighter than ever.
Understanding the Basics of PTA Billing
Let’s start with the foundation. Physical Therapist Assistants are licensed healthcare professionals who work under the direction and supervision of a licensed Physical Therapist (PT).
While they can perform many hands-on treatments, they cannot conduct initial evaluations, make clinical decisions, or change the plan of care. But they can deliver skilled therapy services once the PT establishes those elements.
Billing, however, depends on:
- Payer type (Medicare, commercial, workers’ comp, etc.)
- Supervision level
- Time spent by the PTA vs. PT
- New 2025 modifiers and payment differentials
Medicare’s 2025 PTA Billing Rules: What Changed?
Medicare introduced a 15% payment differential for PTA-provided services that became fully enforced in 2022—and it’s still in effect for 2025. Here’s what it means in plain English:
If a PTA provides more than 10% of a service (based on timed units), and it’s a service eligible for the differential, Medicare pays 15% less than it would if a licensed PT provided it.
The CQ Modifier
This is the most important billing element when dealing with PTAs under Medicare.
- What it is: The CQ modifier indicates the service was furnished in whole or in part by a PTA.
- When to use it: When a PTA provides more than 10% of a billed service.
- What happens if you don’t use it? You could be audited, and Medicare may claw back overpayments or deny claims altogether.
Key Rule: The 10% De Minimis Standard
Here’s how it works:
- If a PTA performs 10% or less of a service, you don’t need to add the CQ modifier.
- If a PTA performs more than 10%, you must use the modifier, triggering the 15% reduction.
Example: You bill a 15-minute therapeutic exercise (97110). If the PTA performs 2 minutes (13.3%), that’s above the threshold. The CQ modifier applies. Medicare pays 85% of the allowable fee.
This small detail adds up. If not monitored closely, your clinic could lose thousands in revenue.
Private Payers vs Medicare: Do They Follow the Same Rules?
Not always. While some commercial payers have adopted Medicare’s PTA rules, many still reimburse the full amount regardless of whether a PTA or PT delivered the service.
Here’s the challenge: each payer has its own policy, and they can change anytime.
That’s why PT Billing stays in constant contact with your payers and audits reimbursement rates to spot discrepancies—before they affect your bottom line.
Common Mistakes Clinics Make When Billing for PTAs
1. Forgetting the CQ Modifier
We see this all the time—especially with new hires or when therapists are splitting visits. Miss the modifier, and you could end up flagged in a Medicare audit.
2. Overlooking the 10% Rule
Even if the PTA only provided a few minutes of a 15-minute service, it might still count as more than 10%. That’s why exact time tracking matters.
3. Billing for Services PTAs Aren’t Allowed to Provide
Initial evaluations, discharge summaries, and clinical progressions must be performed by a licensed PT. Billing for these under a PTA’s work is a fast track to denial.
4. Assuming Private Payers Follow Medicare Rules
Some do. Some don’t. And many won’t tell you unless you ask—or unless your claim gets denied.
Supervision Levels: What’s Required?
Supervision matters. The level of oversight required depends on the setting and payer.
- Outpatient settings (Medicare Part B): Only general supervision is required. That means the PT doesn’t need to be onsite but must be available.
- Private insurers: May require direct supervision (PT on-site), especially for certain services.
- Hospital and SNF settings: Often have different requirements, so double-check.
The key is to document the supervision level clearly in your records.
Documentation Do’s and Don’ts for PTA Billing
Your documentation needs to reflect:
- Who performed the service
- Time spent by each provider
- That the service was provided under the PT’s direction
- Clinical justification for why the PTA performed the service
If it’s vague or looks like a “copy-paste” job, it’s a red flag in an audit.
Pro tip: PT Billing provides PTA-specific documentation templates and training to help your team stay compliant and audit-ready.
How to Prevent Denials When Billing for PTAs
Here’s how we help our clients avoid costly errors:
1. Use Time-Based Tracking Tools
We make sure every unit has clear timing and that PTA time is automatically calculated against the 10% threshold.
2. Educate Your Team
Your PTs, PTAs, and front desk staff need to know the rules—not just your billing team. We provide workshops and quick-reference guides to keep everyone aligned.
3. Pre-bill Claim Auditing
Before a claim goes out, PT Billing scrubs it for CQ modifiers, supervision levels, and payer-specific quirks.
4. Monitor Denial Patterns
If you’re getting multiple denials tied to PTA services, something’s off. We analyze denial codes and feedback from payers to fix the issue at its source.
Scaling with PTAs—The Right Way
Don’t let billing fears stop you from leveraging PTAs. They’re a smart way to grow your clinic, expand your schedule, and deliver high-quality care—as long as your billing is dialed in.
At PT Billing, we don’t just send claims—we help physical therapy clinics build sustainable billing systems that include:
- Real-time PTA billing alerts
- CQ modifier automation
- Documentation coaching for PTAs
- Payer-specific billing policies
- Monthly audit reports
You do the healing—we’ll handle the headache.
Ready to Simplify PTA Billing?
If you’re unsure about how much you’re losing due to incorrect PTA billing—or just tired of second-guessing your claims—PT Billing is here to help.
Let’s take a look at your current process, identify where the gaps are, and build a plan to maximize your reimbursements without risking compliance.
Book your free PTA billing consultation today and discover how much smoother things can run.