How to Bill for Unlisted Codes in Medical Billing

In medical billing, an unlisted code is used to report a service or procedure that does not have a specific Current Procedural Terminology (CPT) code. Reimbursement for these services can be nuanced and complex, but can be navigated with some basic understanding.

“There are specific reasons why the procedure you want to perform may not have its own code,” said R. Peter Manes, MD, coordinator of health policy and chair of the Physician Payment Policy Workgroup for the American Academy of Otolaryngology–Head and Neck Surgery (AAO/HNS). “The most common of these are low volume and newer technology.”

Don’t Use CPT Codes That Are Similar

While you need to be careful when working with unlisted codes, there is no need to fear them. Because of payment concerns, there may be a temptation to use an established code for a similar procedure.

“The listed CPT codes are very precise,” said Lawrence Simon, MD, CPT advisor for AAO/HNS. “There is not a lot of ambiguity in them, so you don’t want to use a code that is close to what you did. If it isn’t exact, use an unlisted code.” Each code grouping has its own unlisted code. For example, 42699 is used for an unlisted procedure of the salivary glands or ducts.

Picking a Comparator Code

You will need to pick a comparator code (CC) to submit as a benchmark for your fee. This is an established code representing a similar amount of time, difficulty or intensity and is the basis for payment. The billing should still be submitted under the code for an unlisted procedure. The CCs are part of the information included to support the billing code.

“The CC, when possible, should be something you do often so you are familiar with the time and intensity commitment,” said Dr. Simon. “But you don’t have to use a CC in the same family as the unlisted code. For example, you could compare an unlisted ear code with a listed tonsil code.”

Documentation Is Important

Documentation should be thorough when claiming an unlisted procedure or service. Describe it in simple, straightforward language telling what was done and why. Outline two or three things that make the unlisted procedure either more or less difficult than your CC. Payers may require a copy of the operative note or other backup material. Every provider has different requirements, so involve them in the process as early as possible.