Coding Faux Pas: 5 Common Rehab Therapy Billing Mistakes

As the old saying goes, “To err is human.” But when human error stands between you and timely reimbursements, it’s difficult to remain philosophical. From missing GP modifiers to miscalculated coding units, here are five common billing mistakes that keep rehab therapists from getting paid.

Article continues after ad.

1. Omitted Modifiers

Modifiers: Easily applied; even more easily overlooked. Therapy modifiers—including GP, GO, and GN—specify to the payer what kind of therapy service was provided (e.g., physical, occupational, or speech therapy). When a payer requires this modifier, the provider will typically need to apply it to every CPT code on the claim. Modifier 59, on the other hand, requires a little more finesse. In a nutshell, this modifier indicates that two linked services were actually performed separately and independently of one another. So, to get paid for both codes in an edit pair, providers typically must append modifier 59 to one of the codes. Fortunately, resources such as this 59 modifier chart can take a lot of the guesswork out of this process.

Another common modifier conundrum: knowing when to use the KX modifier. To receive reimbursement for services provided to a Medicare patient after that patient has reached the annual therapy cap, rehab therapists must affix this modifier to all claims billed above the cap. It sounds simple, but it’s easy to overlook—and ensuring that KX is applied correctly the first time means CMS will process your claims sooner. And that, in turn, means you’ll get reimbursed sooner. Now there’s a win-win.

2. Missing Certifications

I know—chasing down physicians’ signatures can be, well, a challenge. However, having a documented and signed plan of care is crucial to keeping Medicare auditors at bay. And more importantly, it ensures that you’ll get paid for the time you spend treating your patients.

Get Those Signatures—Stat!

The easiest way to combat potential certification compliance issues? Taking care of any and all requirements upfront—before you begin treating the patient. So, be sure to send your plan of care document and dates to the certifying provider ASAP. As compliance guru Tom Ambury explained in this blog post, if you are unable to obtain certification within 30 days of the patient’s initial therapy visit, then “additional documentation is required to explain why it took more than 30 days to get certified and…[that] reasonable attempts [were] made to get the plan certified.” The long and short of it: You absolutely must follow up with the physician’s office to get every certification and recertification returned in a timely fashion—signed, sealed, delivered.

3. Misuse of the Therapeutic Exercise Code

Oh, TherEx—a rehab therapist’s best friend. Good old 97110 will always be there when all else fails, right? Well, not exactly.

A number of therapists fall victim to the therapeutic exercise trap simply because it’s a comfortable and seemingly generic code. However, if you’re constantly using 97110 as a coding catch-all, then you might be missing out on money you’re entitled to. For example, if you’re having your patient work with exercise equipment, or your patient is doing large body movements, there’s a good chance you should be billing for therapeutic activity, which actually has a higher payment rate. Worse yet, according to this article from BMS Practice Solutions, relying too heavily on 97110 can actually trigger an audit if the payer feels it’s being overused.

4. Underbilling Fixed-Rate Payers

Fixed-rate payers—sometimes know as per diem or “capped” payers—have a reputation of throwing folks for a loop. The term “fixed rate” is a bit of a misnomer, and it leads many rehab therapy professionals to believe they will always receive the same amount of reimbursement, regardless of time spent with the patient. This often results in underbilling, because the therapist leaves out unit numbers for timed codes. The truth is that these payers usually reimburse up to a certain capped amount, so if you’re billing for a total reimbursement amount that’s less than the cap, you could be leaving money on the table. The moral of the story: Always apply the appropriate number of units to reflect the amount of time spent with the patient, even if the insurance provider has a so-called “fixed rate.”

5. Miscounted time

“Time, time, time is on my side.” While I’m fairly certain Mick Jagger never moonlighted as a rehab therapist, that line certainly applies to billing for therapy sessions. The simplest way to ensure you’re maximizing your reimbursements is to keep track of all the one-on-one time you spend with the patient—from the moment you begin your assessment with a “Hi, how have you been feeling since your last visit?” (Remember, you should account for your assessment and management time when calculating total treatment minutes.)

You can also bill for the time you spend on the phone with the patient’s referring physician, as well as any time spent documenting. Yes, seriously. There’s just one caveat: you can only receive reimbursement for these activities if you are simultaneously treating or consulting with the patient. But, there should be at least some crossover. After all, it’s best practice to complete your documentation during your patient’s therapy session to help guard against accidentally leaving out vital treatment information.

Note “In and Out” Time If Necessary.

Sorry, West Coasters; I’m not talking about hamburgers. A commonly held belief in the rehab therapy community is that providers must record an “in” time and an “out” time for every session. But, I have good news: according to this article from BMS Practice Solutions, this requirement changed in 2007. However, be aware that a few non-Medicare payers—including some workers’ comp carriers—may still require time logs. But, you shouldn’t “indicate ‘In and Out’ time for every payer and visit as you are only providing an auditor with even more detail to scrutinize against your scheduling program.”

Know the Difference Between Timed and Untimed Codes.

For 8-minute rule purposes, it’s important to know how much time you spend performing time-based procedures versus service-based procedures. However, if you’re worried about timing service-based codes—like the new PT and OT eval codes—to maximize your reimbursements, you can breathe a sigh of relief. As WebPT’s Brooke Andrus explains in this blog post, when it comes to service-based codes, “you can’t bill more than one unit—regardless of the amount of time you spend delivering treatment.” In other words, the reimbursement amount for these codes isn’t affected by the length of time a provider spends performing the associated services. So, keep that in mind when tracking minutes for these procedures.


Even the most billing-savvy rehab therapist will tell you that staying compliant with billing best practices is no easy feat. That’s why keeping yourself updated is so essential to your success. You can keep yourself immersed in the discussion by engaging in online communities and attending conferences. Many payers, such as CMS, also distribute email alerts to help you stay in the loop on industry and compliance changes. Taking advantage of these resources will ensure you stay on top of your billing game—and keep your practice moving forward on the road to success.


Stay on top of the latest rehab therapy tips, trends, and best practices.

7 min. read

Achieve greatness in practice with the ultimate EMR for PTs, OTs, and SLPs.