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Physical Therapists’ Guide to Billing

With our guide to billing, physical therapists and other rehab professionals can get best practices on coding, modifiers, and more.

Heidi Jannenga
5 min read
February 8, 2023
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You became a physical therapist to help people; you didn’t do it for the money. But in order to stay in business long enough to actually make a difference in your patients’ lives, you absolutely must bill—and collect payment—for your services. (How else do you plan to keep the lights on?) For physical therapists, physical therapy billing is a fact of life, but that doesn’t mean the process should be overwhelming. And that’s true whether you’re a seasoned veteran or a fresh graduate.

Read on to learn everything you need to know about physical therapy billing—well, a lot of it, anyway.

What are the codes?

The International Classification of Diseases (ICD)

In order to successfully bill for your services, you’ll need to provide a diagnosis for your patients’ conditions in a manner that demonstrates the medical necessity of those services—and you’ll need to do so using the latest version of the International Classification of Diseases (ICD), which, as of October 2015, is ICD-10. Given the complexity of the new coding system, it can be difficult to decide which code—or codes—to use. To help navigate this territory, the American Physical Therapy Association (APTA) created this shortcut list of ICD-10 categories.

If you’re ever in doubt as to whether your codes are reimbursable under your payer’s payment policy, call the payer before submitting the claim. According to the APTA, “Your goal is to maximize the number of claims that are paid on the first submission and to minimize the need for appeals.” In other words, in this case, it’s much better to ask for permission than for forgiveness.

The Current Procedural Terminology (CPT)

Developed by the American Medical Association (AMA), the Current Procedural Terminology (CPT®) is “the most widely accepted medical nomenclature used to report medical procedures and services under public and private health insurance programs.” According to the APTA, “When billing most third parties for services…it is necessary to utilize CPT-4 codes to describe the services that were rendered. Although CPT is not an exact description of physical therapists’ interventions, it does provide a reasonable framework for billing.”

Most of the CPT codes that are relevant to rehab therapists are located in the 97000 section (“Physical Medicine and Rehabilitation”). However, you can bill any code that best represents the service you provide as long as you can legally provide that service under state law. Be forewarned, though: just because you can legally bill for a code doesn’t automatically mean that a payer will reimburse you for it. When in doubt, always check with your payers before providing the service in question.

All physical and occupational therapists should get to know the following CPT categories before billing for their services:

Learn more about CPT codes for physical therapists.

One-on-One Services vs. Group Services

If you’re providing group therapy services, you should not use one-on-one CPT codes, because this can increase your risk of an audit. So, what are one-on-one services? They’re individual therapy services—ones that involve direct, one-on-one contact with a patient. During her Ascend 2015 presentation, Deb Alexander explained that these codes are cumulative, require constant attendance, and are time-based, which—as this article points out—means that the 8-minute rule applies. (Check out this blog post to see how many units you can bill based on treatment time.)

Now, even if you’re working with more than one patient at a time, you still can provide—and bill for—one-on-one services. That’s because CMS allows these one-on-one minutes to occur continuously or in intervals—as long as those intervals are “of a sufficient length of time to provide the appropriate skilled treatment in accordance with each patient’s plan of care.”

Group therapy still requires constant attendance, but it does not involve one-on-one contact with the patient. Rather, CMS writes that it “consists of simultaneous treatment to two or more patients who may or may not be doing the same activities.” So, if you’re providing attention to more than one patient at a time with only “brief, intermittent personal contact,” you should bill one unit of group therapy to each patient.


What’s the terminology?

Looking for a refresher on your billing terminology? Here are some definitions we’ve adapted from this APTA resource and this WebPT one to bring you back up to speed:

  • Treatment: Includes all therapeutic services.
  • Time-based (constant attendance) CPT codes: These codes allow for variable billing in 15-minute increments when a practitioner provides a patient with one-on-one services such as therapeutic exercise or manual therapy.
  • Service-based (supervised or untimed) CPT codes: These are the codes therapists use to perform services such as conducting an evaluation or applying hot/cold packs. It doesn’t matter if you complete these types of treatments in 5 minutes or 45, because you can only bill one code.
  • Order (a.k.a. referral): In some cases, a physician will provide an order for therapy that includes a diagnosis and instructions for treatment type, duration, and frequency.
  • Evaluation: The evaluation typically takes place on the patient’s first visit and includes an examination, which consists of a review of historical data and symptoms as well as performance of tests and measures. It is at this point that the therapist provides a diagnosis and prognosis. (Therapists should perform a re-evaluation only when the criteria detailed in this blog post are met.)
  • Plan of care: Based on the evaluation—and the physician’s order, if applicable—the therapist works with the patient to develop a plan of care to help the patient meet his or her therapeutic goals.
  • Initial certification: Medicare requires ordering physicians to “approve or certify the plan of care via signature in a timely manner (within 30 days of the evaluation).” The initial certification covers the first 90 days of treatment. To continue treatment past the first 90 days, therapists must receive re-certification from the ordering physician.
  • Progress report: For Medicare patients, therapists must complete a progress report (a.k.a. progress note) at minimum every tenth visit.
  • Discharge note: Once treatment is complete, therapists must complete a discharge progress report that outlines a patient’s progress from the last 10-visit progress note up until discharge. (Note that writing the progress note and discharge note are not separately billable services for the therapist, but are required for Medicare documentation.)

What are the forms?

Today, most payers—and providers—prefer electronic claim forms. However, some payers—a dwindling few—do still accept paper ones. The most common form is the Universal Claim Form (CMS 1500), although some payers may request that you use their own.

Once you provide your services, you’ll submit a bill to either your patient or a third-party payer. Occasionally, you may actually submit your billing information to a claims clearinghouse that will create the bill and send it out on your behalf.

The Health Insurance Portability and Accountability Act (HIPAA) covers healthcare claims transactions, so be sure your clinic remains compliant with the Electronic Healthcare Transactions and Code Sets Standards.

What are the forms?

Today, most payers—and providers—prefer electronic claim formats. However, some payers—a dwindling few—do still accept paper ones. The most common form is the Universal Claim Form (CMS 1500), although some payers may request that you use their own.

Once you provide your services, you’ll submit a bill to either your patient or a third-party payer. Occasionally, you may actually submit your billing information to a claims clearinghouse that will create the bill and send it out on your behalf.

The Health Insurance Portability and Accountability Act (HIPAA) covers healthcare claims transactions, so be sure your clinic remains compliant with the Electronic Healthcare Transactions and Code Sets Standards.

What should I know about electronic claims?

There’s a lot to know about electronic claim compliance. So, we thought it would be helpful to provide you with the CliffsNotes:

Once all of your digital ducks are in a row, electronic claim forms can seriously expedite payments for your clinic. In fact, it usually takes about two weeks to receive reimbursement for an electronic claim, whereas payment for paper claims can take up to six to eight weeks. And now that 99% of payers accept electronic claims, there’s no real reason you should still be submitting paper claims.

What’s the process?

Choose a software or service.


A lot of providers use a billing software to prepare and submit their claims. The really smart ones use an electronic medical record system that includes (or integrates with) a top-notch therapy billing software (hello, WebPT). That way, they eliminate double data-entry—as well as the errors associated with it. If you go this route, be sure your solution is fully HIPAA-compliant.

You’ll also want to be sure to select a solution that offers the following key features and benefits:

  • Claim tracking
  • ERAs
  • EOB and payment posting
  • Custom reports
  • Clearinghouse integration
  • Patient portal, invoicing, and billing
  • Insurance eligibility verification
  • A super-simple, user-friendly billing interface
  • Detailed activity logs

To learn more about selecting the right billing software for your clinic, read this article. In case you’re wondering, even cash-based practices need a great billing software.

In addition to everything listed above, Therabill offers credit card processing, auto-eligibility checks, a patient portal, an integrated, no-fees clearinghouse, and unlimited claims submission and support—all designed to help you get paid quickly and accurately.

See how WebPT and Therabill can help you maximize your A/R here.


If you’re looking for a more hands-off solution, you could always outsource your billing to a PT-specific billing service whose team of pros will handle all of your revenue cycle management, including maximizing your reimbursements and minimizing denials. That way, you don’t have to think about beefing up your billing staff or staying on top of the often-confusing claims process.

Your practice’s financial health hinges on your ability to produce clean, accurate claims. So, you’ll want to invest in a service that can submit your claims quickly and expedite reimbursements. You’ll also want it to fully integrate with your EMR, so you can ensure a seamless workflow and no-double data entry.

When hiring an RCM service, look for one that has:

  • Experienced billers with regional specialization;
  • A 98.5% first-pass claim acceptance rate; and
  • A near-perfect clinic retention rate.

WebPT has 30 years of outpatient rehab therapy billing experience, making it the largest and most tenured RCM company in the industry. Our RCM team processes more than 11 million claims and visits per year. We’ve officially reached expert status.

Click here to see how WebPT can help take your practice’s billing to the next level.

Even better: Find a rehab therapy-specific solution that prioritizes increased payment per visit and doesn’t get paid unless you do. That way, you can be sure the company will relentlessly post and reconcile payments—and investigate, correct, and appeal claim denials.

Get credentialed.

If you haven’t already received credentialing, you may want to consider changing that. Being credentialed by an insurance company allows you to become an in-network provider, which may help you reach—and serve—a larger pool of potential patients. In fact, a majority of potential patients consider whether a provider will take their insurance when making their decision on where to go for healthcare services. And some payers—like Medicare—do not allow non-credentialed providers to treat or collect payment from patients for any covered services. However, getting credentialed isn’t exactly easy. You have to obtain:

  • malpractice insurance,
  • an NPI,
  • a physical clinic location, and
  • a license to practice in your state.

If you have questions about the credentialing process, consider seeking the advice of a consultant or an established PT in your neighborhood. They may be able to help you complete the paperwork as well as provide tips and tricks for ensuring its acceptance.

Negotiate payer contracts.

Just as rules are (sometimes) meant to be broken, contracts are (always) meant to be negotiated. This especially holds true when it comes to your private payer contracts. After all, these rates establish what you’re able to earn—and that number should be an accurate reflection of the value of your services. Before you broach the subject of a rate increase with your payers, though, here a few things you should do to ensure you’re fully prepared to get the best deal:

Verify patient info.

Before you begin treatment—ideally before your patient even arrives for his or her first appointment—you or your front office staff members should verify patient information, including:

It’s also a good idea to determine whether the insurance company requires a referral or preauthorization before you begin treatment.

Collect copays.

If your patient’s insurance requires them to pay a copay, you can collect that payment when you provide your services. In most cases, it is not a good idea to waive the copayment or the deductible. However, there are other ways to provide financial aid to patients who need it. To learn more about what your payers find acceptable when it comes to helping patients cover the cost of your services, thoroughly read your insurance contracts. If you can’t locate the answers in your contracts, contact the payers directly.

Issue ABNs (when applicable).

In order to provide Medicare patients with services that you believe are either not covered by Medicare or are not medically necessary, you must have your patient sign an Advance Beneficiary Notice of Non-coverage (ABN), thereby assuming financial responsibility if—but really more like when—Medicare denies the claim. To learn more about how to correctly administer an ABN, read this article.

Create defensible documentation.

Ensuring your documentation is defensible is one of the most important things you can do to support your billing processes. This will help you demonstrate medical necessity, and thus, get paid. Plus, if you ever find yourself on the wrong side of an audit, you’ll be happy you spent an extra few minutes thoroughly describing your patient’s history, your skilled interventions, and your clinical decision-making process. It’ll make a big difference in your ability to justify your requests for payment. (For a guide to documenting defensibly—complete with therapy—specific patient examples—download this free resource.)

Make it a team effort.

Complete and accurate billing requires a team effort, because, as we mentioned above, the billing process begins before the patient even enters your clinic—and it doesn’t end until the patient has finished his or her treatment and you’ve gotten paid. Here’s something you can do to ensure your team is playing like—well—a team: teach everyone on your staff clinical terminology. It’s challenging enough to bill correctly if you’re a PT rockstar, but if you don’t understand the difference between an evaluation and an initial certification or a progress report and a reevaluation—forget about it. Planning to work with a lot of direct access patients? You’ll need to brush up on the ins and outs of that, too—and then share your knowledge with your staff.

Still flubbing up your 8-minute rule math? Do you know when and when not to not use modifier 59?

We all make mistakes, but when it comes to billing, those mistakes can cost you—big time. Enter your email address below to view a webinar on some of the most common—and deadliest—PT billing sins.

What are some frequently asked billing questions?

Here are the some of the most common questions PTs, OTs, and SLPs have about billing.

How do I use modifiers?

Modifier 59

You may need to apply modifier 59 if you provide two wholly separate and distinct services during the same treatment period. Learn more about modifier 59 here.

KX Modifier

The KX modifier is part of the KX Modifier Threshold. If you believe it is medically necessary for a patient who has already reached the threshold to continue therapy—thus qualifying the patient for an exception—you would attach the KX modifier and clearly document your reasons for continuing treatment.

GA Modifier

If you issue an ABN because you believe that certain services are not medically reasonable and necessary, then you should add the GA modifier to the claim to signify that you have an ABN on file. (Please note that if you use the GA modifier, you should not use the KX modifier.)

Speaking of ABN-related modifiers, there are three more you should know about:

  1. GX: Indicates that you issued a voluntary ABN for a non-covered service.
  2. GY: Indicates that you performed a non-covered service, but an ABN is not on file. (In this case, the patient is inherently liable for charges because the service is not covered.)
  3. GZ: Indicates that you expect the service to be denied because it isn’t medically necessary, but you do not have an ABN on file. (In this case, the patient is not responsible for payment.)

GP Modifier

Physical therapists should affix the GP modifier for services performed by a physical therapist, as opposed to another provider. This modifier is most frequently used in multidisciplinary settings. (The same goes for occupational and speech therapy plans of care.)

X Sub-Modifiers

CMS has determined for the rehab timed codes, the -59 modifier is the appropriate modifier for NCCI edits. (You can check out Example 9 in this document for further illustration.) CMS has unbundled NCCI edit pairs when providers attach the appropriate modifier (59, XE, XS, XP, or XU) to either the first-column or second-column code (provided that the situation warrants the use of one of these modifiers). Like modifier 59, X sub-modifiers are intended for use when billing for two “linked” codes that are not ordinarily billed together. The difference is that X sub- modifiers offer greater specificity and thus, better justification for billing these codes together. CMS has determined that X sub-modifiers are not usually appropriate with timed CPT codes performed at separate and distinct times in a visit; in those instances, the 59 modifier would be appropriate for use.  

The four X sub-modifiers are as follows:

  1. XE (Separate Encounter): A service that’s distinct because it occurred during a separate encounter
  2. XS (Separate Structure): A service that’s distinct because it was performed on a separate organ/structure
  3. XP (Separate Practitioner): A service that’s distinct because it was performed by a different practitioner
  4. XU (Unusual Non-Overlapping Service): A service that’s distinct because it doesn’t overlap the usual components of the main service

We should note that this change might not affect all Medicare programs or commercial or Medicare Advantage payers—which is why you should contact all non-CMS payers to determine where they stand.

CO and CQ Modifiers

2022 marked the year the PTA and OTA payment differential went into effect. As outlined in the CMS 2022 Final Rule—and in this helpful article—the CQ and CO modifier protocols work like this:

  • “When a PTA or OTA independently provides at least 10% of a service (whether that’s a timed or untimed unit), you must apply a CQ or CO modifier, respectively.
  • When a therapy assistant provides a service in tandem with a PT or OT, those minutes do not count toward the 10% de minimis benchmark.
  • If a therapy assistant furnishes more than 10% of one unit of a service, “but does not contribute to other units of that same service, then you can split the service into two different claim lines and apply CQ or CO only to the applicable units.”

The de minimis rule (i.e., the 10% benchmark) will not apply ‘when the OT/PT provides more than the midpoint of a 15-minute timed code, that is, 8 or more minutes, regardless of any minutes for the same service furnished by the OTA or PTA.’”

What does “locum tenens” mean?

“Locum tenens” means “placeholder” in Latin. In medical billing terminology, it refers to a person who temporarily fulfills the duties of another. While physicians may simply add a modifier to the treatment claim to indicate that a replacement physician provided those services, most PTs, OTs, and SLPs may not. As we explained in this blog post, “as of June 13, 2017, private practice PTs—Provider Specialty 65—who practice in ‘non-metropolitan statistical areas, medically underserved areas (MUAs), and health professions shortage areas as defined by the US Department of Health and Human Services’ can take advantage of locum tenens arrangements.” That said, even providers who meet the above-listed criteria can only bill Medicare for services performed by a locum tenens PT under the regular PT’s NPI—if they are absent for a limited period of time for vacation, disability, continuing education, etc., and the following conditions are met:

  • The regular PT is not available to provide care.
  • The replacement PT is compensated on a per diem or similar fee-for-time basis.
  • The regular PT doesn’t use locum tenens for more than 60 continuous calendar days. (If the regular PT returns to work and must leave again, he or she may re-hire the same locum tenens PT and a new 60-day period begins.)
  • The PT uses a modifier [Q5 or Q6] to indicate that the services were provided by a locum tenens PT.

It may also be important to note that in 2017, CMS decided that it would no longer refer to this type of an arrangement as “locum tenens,” yet it did not propose a replacement term. For the sake of clarity and continuity, we have decided to continue using this phrase until a better solution becomes available.

Providers who do not practice in MUAs, HSPAs, or rural areas must solve what is often referred to as the “bill as” problem by only hiring temporary employees, contractors, and travel PTs who are fully credentialed with the same insurance companies that provide benefits to their patients (and that’s especially important for Medicare). The best way to do that is usually to hire through a qualified staffing agency with verified credentials.

Learn more about billing for temporary staff here.

What is MPPR?

In 2011, CMS began reducing payments to therapists when they performed multiple therapeutic procedures on one patient during the same date of service. This policy is known as the Multiple Procedure Payment Reduction (MPPR). During the pioneer years of MPPR—January 1, 2011 to March 31, 2013—PTs, OTs, and SLPs saw a 20% reduction to the practice expenses (PE) they billed to Medicare for these “always covered” services. Since April 2013, that figure has increased significantly, as therapists now must contend with a 50% cut to their PE when performing these services. Learn four key things you should know about MPPR changes here and how to manage MPPR in your clinic here.

What is the 8-Minute Rule?

The 8-Minute Rule determines how many service units therapists can bill to Medicare for a particular date of service. According to the rule, you must provide direct treatment for at least eight minutes for each unique service in order to receive reimbursement from Medicare for time-based codes. Learn everything you need to know about the 8-Minute Rule.

How do I bill for co-treatment?

There are times when co-treatment may be appropriate—specifically, when therapists of different disciplines determine that they can better address a patient’s treatment goals and needs if they provide their individual treatments during a single session. (You can find some examples here.) That said, payers have different rules for co-treatment based on coverage type and setting. We’ve compiled Medicare’s rules below; for your commercial payers, you’ll need to review your contracts and/or reach out to payers directly to learn about their rules.

Medicare Part A

When two therapists from different disciplines provide different treatments to one patient at the same time in an inpatient rehab facility, acute care setting, home health setting, or skilled nursing facility, each therapist should bill his or her full treatment session with that patient separately. As Meredith Castin, PT, explains in this blog post, “If an OT and a PT co-treat from 10:30 AM to 11:30 AM, and the OT works on toileting strategies while the PT simultaneously addresses safe transfers, both clinicians could bill for that entire hour, provided they show proof of providing separate treatments with separate end goals.” In all situations, though, the plan of care and documentation must support the need for co-treatment—and, as we’ll explain in a moment, the need cannot be based on provider convenience. Additionally, all providers must follow all policies regarding mode, modalities, and student supervision as well as all other federal, state, practice, and facility policies.

Medicare Part B

By contrast, therapists who practice in facilities and clinics that bill under Medicare Part B cannot bill separately for the same or different service provided to the same patient at the same time. That means therapists must limit total billing time to the exact length of the session. In other words, the therapist of one discipline may bill for the entire service or the co-treating therapists of different disciplines may divide the service units. ASHA provides the following guidance for scenarios in which a PT or OT co-treats with an SLP: “Because SLPs usually bill treatment codes that represent a session (rather than an amount of time), and because Medicare has no published minimum/maximum session length, the SLP would bill for one untimed session.” Then, the OT or PT would bill “the timed treatment codes for the occupational or physical therapy.”

The Rules

As we explained in this guide, the American Speech-Language-Hearing Association (ASHA), American Occupational Therapy Association (AOTA), and American Physical Therapy Association (APTA), developed joint guidelines for both Medicare Part A and Part B stating that therapists should only co-treat a patient when doing so directly benefits the patient. Therapists should never co-treat for “scheduling convenience.” As Castin explained in the above-cited post, it’s important to note that while “therapists often opt to co-treat for safety reasons…simply having a second person on hand to act as a contact guard (i.e., to prevent falls) is not enough to justify billing for a second therapist’s services.” Regardless of the setting, documentation for co-treatment must clearly indicate the therapists’ rationale and specify the goals each therapist is addressing. And it’s not enough for one therapist to document—even if that one therapist is billing for the entire session. Instead, both therapists should document co-treatment sessions with enough detail to convey the goals the team of therapists addressed—as well as how the patient is progressing as a result. It’s also advisable to limit therapy services performed during one treatment session to two disciplines.

Modifiers 59 and XP

Practices and facilities that offer their patients both physical and occupational therapy may need to affix modifier 59 or modifier XP to claims when patients receive same-day services that form NCCI edit pairs. According to Castin, modifier XP would be appropriate if, say, “an OT takes over treatment in the middle of a PT session” and modifier 59 would be appropriate if the payer doesn’t yet recognize X modifiers or there’s another reason to provide “otherwise linked services that should, given the circumstances, be reimbursed separately.” For example, you would use modifier 59 if, say, a PT provides gait training (97116) and an OT provides therapeutic activity (97530). As such, you’re notifying Medicare that the services—97116 and 97530—were performed separately and distinctly from one another and thus, should both be paid.

What billing behaviors should I avoid?

If you’re billing Medicare, here are a few risky behaviors to steer clear of:

  • Billing for services furnished by aides or techs
  • Submitting claims for services that you know are not reasonable and necessary
  • Billing for excessive duration and frequency of services
  • Billing under another rendering provider

What should I know about ICD-10 and my billing claim forms?

  1. The current 1500 claim forms accommodate ICD-10 codes.
  2. You should still use CPT codes to denote services provided.
  3. You can list up to four diagnosis pointers per service line.
  4. You should order multiple diagnosis codes according to significance.

For more ICD-10 billing tips, check out this post.

When should I bill for a re-evaluation?

You should only bill for a re-evaluation if one of the following situations applies:

  • You note a significant improvement, decline, or change in the patient’s condition or functional status that was not anticipated in the plan of care (POC).
  • You uncover new clinical findings during the course of treatment that are somewhat related to the original treating condition (i.e., a new diagnosis to add to the POC).
  • The patient fails to respond to the treatment outlined in the current POC, so a change to the POC is necessary.
  • You’re treating a patient with a chronic condition, and you don’t see the patient very often.
  • Your state practice act requires re-evaluations at specific time intervals.

WebPT’s co-founder and president, Heidi Jannenga, discusses this topic in great detail here.

What constitutes billable time?

In most cases, billable time is the time spent treating a patient. However, there are some notable exceptions (e.g., you can’t bill for supervision). Check out this blog post to learn more about when to bill and when not to bill.

Need to get a handle on your billing processes?

Sometimes billing feels like a guessing game—one that can leave you scratching your head over claim rejections and denials. That’s why we created the Complete Guide to Physical Therapy Billing, a comprehensive resource to help you get your billing processes in tip-top shape. Simply enter your email address below, and we’ll send it your way.


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