Question: Recently at out neurosurgery clinic, I heard one of the coders tell the other to use a “cat 3” code for a procedure. What is a “cat 3” code, and how does it differ from other CPT® codes?
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Answer: This coder was speaking of CPT® Category III codes, which are also known as T codes. The AMA explains that “CPT® Category III codes are a set of temporary codes that allow data collection for emerging technologies, services, procedures, and service paradigms. These codes are intended to be used for data collection to substantiate widespread usage or to provide documentation for the Food and Drug Administration (FDA) approval process.”
You’ll find T codes in the 0042T-0947T Category III section of the 2025 CPT® code book.
Caveat 1: Payers won’t always reimburse Category III codes. These decisions will be payer-dependent, as the codes are not Category I codes. However, the AMA created these codes to gauge how often the procedures are performed, so that the procedure could potentially become a Category I code in the future. Reach out to the payer to see if it reimburses each specific Category III code — some payers will pay for certain T code procedures but not others, while some payers don’t recognize T codes at all.
Caveat 2: T codes are updated twice a year, every January and July. In order to stay atop the Category III codes, you’ll need to pay attention to the updates the AMA will publish this summer.
You can look through the Category III codes section to see if any of the codes match procedures your neurosurgeons might be performing. In 2025, these neurosurgery-relevant codes were new to the Category III section:
Chris Boucher, MS, CPC, Senior Development Editor, AAPC
