If you are a healthcare provider or part of a billing team that is dealing with claim denials for a new device or an emerging diagnostic procedure, you must have come across a 5-digit code that ends with the letter “T”. These 5-digit codes are usually in practice called the T codes; however, they are still CPT codes, CPT Category III codes, to be specific.
Unlike normal CPT codes that are used to bill established services, procedures, and tech, the T codes in medical billing are used to track and bill the technology and procedures that are still new to medical use and under experimentation.
We have created this guide to help you understand what these codes are, how they work, how they are different from normal CPT codes, and the best practices that you should follow while using them. So, let’s start.
Significance of T Codes in Medical Billing
Before we start with the working mechanism of these codes, let’s first briefly discuss why T codes in medical billing are important.
These codes matter a lot because using them incorrectly or not using them altogether will have a significant effect on the practice’s revenue. What you must note here is that if you are filing a claim for a service for which a T code exists, you should use that code instead of an unlisted Category I code. Not following this will result in a claim denial.
Their reimbursement is also not the same as other CPT codes. Since they track emerging technologies, reimbursement is rarely automatic. Most Category III codes carry no assigned relative value units and no set Medicare payment rate. This means the amount a practice gets, if it gets paid at all, depends on the payer’s own coverage policy and on the documentation submitted with the claim.
So, focusing on documentation is very important for these codes.
Understanding How T Codes Work
We have already explained what T codes are and why they are important. Let’s now dig a little deeper. Category III CPT codes are formally defined as:
“A set of temporary codes that allow data collection for emerging technologies, services, procedures, and service paradigms, intended to substantiate widespread use of a service or to support the FDA approval process.”
Actually, the Category III codes serve two purposes:
- They let the AMA and payers track how often a new procedure or device is actually being used.
- They create a formal pathway for a new service to eventually earn a permanent Category I code, once enough utilization and outcomes data have accumulated.
The T codes are temporary codes. They can remain active for up to 5 years. If, after 5 years, the codes are not converted into permanent Category I codes, they are either extended or archived. In this case, the providers are advised to use Category I unlisted codes.
How Do T Codes Differ from Other CPT Codes?
The easiest way to understand T codes in medical billing is to compare them directly with Category I codes. Take a look at the following table:
| Feature | Category I Codes | Category III (T) Codes |
|---|---|---|
| Purpose | Report established, widely accepted procedures and services. | Track emerging technologies, services, and procedures. |
| Code Format | Five numeric digits. | Four digits followed by the letter T. |
| RVUs & Payment | Assigned relative value units and a set Medicare fee schedule amount. | No assigned RVUs; payment is carrier-priced and payer-specific. |
| FDA Requirements | Devices and drugs generally must have full FDA clearance or approval. | May not conform to the usual FDA clearance requirements. |
| Duration | Permanent, unless deleted or revised. | Temporary; archived after five years unless extended or converted. |
| When to Bill | Use whenever the code accurately describes the service performed. | Must be used instead of an unlisted Category I code when applicable. |
Examples of Category III (T) Codes
The range of Category III CPT codes is extensive. That’s why the American Medical Association (AMA) revises them twice every year. This is usually done once in January and once in July. Because of this constant turnover, providers should never treat any list of T codes, including the one we have shared below, as complete or permanent.
Important Note: In August 2026, the AMA announced that it has changed its “early release schedule for CPT® Category III codes to three updates per year instead of two”. So now, the CPT Category III codes will be revised and published every year in April, July, and October.
That said, a few examples of these codes are:
- 1029T: Mapping & programming neurostimulation catheter in ventilated patients without repositioning.
- 1037T: Histotripsy malignant pancreatic tissue with imaging guidance.
- 1046T: Autologous heterogeneous skin-construct graft application, trunk, arms, legs; 1st 50 cm2 or less.
- 1078T: Decannulation of liver allograft from hypothermic oxygenated perfusion device.
- 1056T: Cochlear infusion pharmacologic agent.
Documentation Requirements for T Codes
We have already mentioned above that T codes don’t have a fixed reimbursement rate, and it depends on the payer policy. That’s why documentation has more weight for these codes than normal CPT codes. With each claim, you should try to provide the following:
- A detailed operative or procedure note describing exactly what was done.
- Clear justification of medical necessity.
- Proof that every page of the record is legible and includes the patient’s name and date of service.
- A signed and dated note from the physician or non-physician practitioner responsible for the care.
Please note that these are just the bare minimum requirements. Always try to provide comprehensive documentation and medical records with each claim.
Best Practices for Providers Billing T Codes
To reduce denials and collect what you are owed, you should:
- In your charge masters and EHR, add the T codes. This way, the billing staff will be able to identify when to use Category III codes and when to use unlisted CPT codes.
- Confirm payer-specific coverage and prior authorization requirements.
- Submit complete, legible documentation with every claim.
- Track each T code’s reimbursement outcome to identify which payers reliably cover the service, and at what rate.
Final Thoughts
It’s time to wrap up this guide. In this guide, we explained what the T codes in medical billing are, why they are important, and how you can use them in your claims. Here is a quick recap:
- T codes are temporary, five-digit codes ending in the letter “T”. They track emerging medical technologies and procedures.
- They must be used instead of an unlisted Category I code whenever one applies.
- The AMA updates the Category III list three times a year, effective August 2026.
- Detailed documentation is vital for these claims.
If your practice needs help with billing, you can opt for medical billing and coding services provided by experts at NeuraBill. Not only will they take over intricate coding, but they will also ensure that error-free claims are submitted on time.
