CPT Code 99999: Unlisted procedure, general

Learn how to correctly document and bill CPT code 99999 for unlisted general procedures and services, including documentation requirements.

Use Code

What is the 99999 CPT code?

CPT code 99999 is an unlisted procedure code used when no specific code exists in the Current Procedural Terminology (CPT) code set, maintained by the American Medical Association (AMA). It is designed to report general medical services or procedures performed by healthcare providers that are not defined by existing CPT codes and do not fall under a more specific section (e.g., surgical, radiologic, or evaluation and management categories).

This code may be used for emerging technologies, complex medical procedures, experimental interventions, or services that are new to clinical practice and have not yet been assigned a temporary CPT code. Because 99999 is broad in scope, it is subject to manual review and must be supported by detailed documentation for coverage consideration.

Documentation requirements

When billing CPT 99999, thorough and clear medical records abstraction is essential to justify the nature, complexity, and necessity of the service.

Service description

Clearly describe the procedure or service performed, including why it does not fit any existing CPT code. Include technical details, the type of physical examination or intervention conducted, and any equipment or technology used.

Medical necessity

Document the clinical reason the service was performed and how it benefits the patient’s care. The medical record should show why this general or unlisted service was necessary and how it fits within accepted standards of care or emerging best practices.

Comparison code and rationale

When possible, reference a similar CPT code (in complexity or time involved) to help Medicare Administrative Contractors (MACs) and commercial payers assign relative value. This is especially helpful when billing through systems governed by the National Correct Coding Initiative (NCCI).

Supporting materials

Attach any relevant clinical notes, operative reports, and a short cover letter explaining the service. If applicable, include evidence from peer-reviewed studies or clinical guidelines.

Billing and guidelines

To ensure accurate billing, providers must submit detailed supporting documentation, follow the coding guidelines outlined by the American Medical Association, and understand how to navigate potential reimbursement challenges.

Unlisted and manually priced

CPT 99999 is not assigned a set fee and is manually priced by each payer. Submit the claim with all supporting documentation and a suggested comparison code to facilitate review. Medicare services billed under 99999 may require additional review or preauthorization, depending on the Medicare Administrative Contractor (MAC).

Not billable with standard codes

Do not report CPT 99999 in combination with other CPT codes for the same service. Use it only when there is no more appropriate option available in the CPT code set.

Temporary or emerging services

Use 99999 for temporary procedures or services not yet assigned a Category I or III code. Check AMA updates periodically, as newly recognized procedures may receive a temporary code that replaces 99999.

Other related CPT codes

99499 – Unlisted evaluation and management service
49659 – Unlisted laparoscopy procedure, hernia repair (example of unlisted surgical CPT)
64999 – Unlisted procedure, nervous system

Frequently asked questions

CPT 99999 is used for general medical procedures or services not described by any existing CPT code. It’s often used for new, rare, or experimental procedures pending formal code assignment.

Payers, including Medicare, may cover CPT 99999 if the service is medically necessary and documentation supports its use. However, coverage is determined on a case-by-case basis and is subject to manual review.

Many payers require preauthorization or prior review for unlisted codes like 99999. Always check payer-specific requirements before performing the service.