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Timed and Untimed: A Tale of Two Physical Therapy Billing Codes

Knowing the difference between timed and untimed CPT codes can make a world of difference in your billing practices.

Melissa Hughes
5 min read
May 25, 2021
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It was the best of times; it was the worst of times. It was the age of billing; it was the age of declining reimbursements. It was the epoch of regulatory change; it was the epoch of—well, you get the point. Charles Dickens sure knew his way around a turn of phrase, and it’s no accident that the first few lines of A Tale of Two Cities were so dang iconic and timeless. And while my rehab therapy billing parody may have taken a bit of the shine out of his prose (sorry about that, Mr. D!), we’re going to forge onward and talk about two other “opposites”: timed and untimed codes. These code classifications are a cornerstone of accurate physical therapy billing, so pull out your quill and paper—I mean, your notes app—and get ready to learn!

What do I need to know about timed and untimed codes?

Put simply, the CPT® Professional Edition manual classifies codes as timed or untimed in an effort to regulate billing. Untimed units may be billed once per date of service per patient—regardless of how much time a therapist spent providing the associated treatment. Timed codes may be billed multiple times per date of service per patient in accordance with the amount of time the therapist spent providing the treatment.  

What is the definition of a timed code? 

Timed codes require the furnishing provider (e.g., the therapist) to remain in constant attendance with—and/or provide constant contact to—the patient receiving the service. In other words, these one-on-one services are typically very involved and hands-on—and as a result, they occasionally pay better than untimed service-based codes. 

Common Timed PT Codes 

Here are some timed codes that physical therapists commonly bill:

What is the definition of an untimed code?

Despite how it may sound, untimed codes (a.k.a. service-based codes) are not the true opposite of timed codes. Rather, untimed codes can be either attended or unattended—though they’re always considered session-based. Yeah, I know. It’s a little confusing!  

Common Untimed PT Codes 

Here are some untimed (or service-based) codes that physical therapists commonly bill:

How do I know if a CPT code is timed or untimed?

Best practice is to refer to the hard copy of your CPT manual. If a CPT code has a “distinct unit of time listed in [its] descriptor,” then according to the ASHA website, it is officially considered a timed code. Untimed codes, however, “do not include time units in their descriptors.” So if a CPT code description says something like “every 15 minutes,” then rest assured that it is timed. If a code description is missing units of time completely, then the code is session-based.

If you don’t have a CPT manual, the AAPC has a pretty nifty CPT lookup tool that can typically provide the information you need. 

How do I bill timed and untimed codes? 

Let’s start with the easier of the two: untimed codes. As mentioned above, you may bill one unit of each untimed service per patient per date of service. Whether you provide an untimed service for five minutes or 50, you will always bill one single unit. 

Timed Codes and the 8-Minute Rule

Timed codes are a little more complex, because they’re governed by either CMS’s 8-minute rule or the AMA’s rule of eights. These rules basically allow providers to bill services in 15-minute increments. So, if a PT provided manual therapy for 15 minutes, then they could bill one unit. If that PT provided manual therapy for 30 minutes, they could bill two units—and so on and so forth. 

However, as you probably know, PTs very rarely provide services for exactly 15 minutes. So, according to the 8-minute rule, if a service is provided for eight or more minutes, the therapist can bill one additional unit. For more detailed information on how the 8-minute rule differs from the rule of eights, check out this blog post or this guide.

While A Tale of Two Cities may be more entertaining to read than a blog post on PT billing, here’s hoping that you’re left headed toward the best of times—and away from the worst of times.

Have lingering questions about timed and untimed codes? Feel free to drop ’em below, and our team will do its best to answer them. 


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