Integral to billing medical services and procedures for reimbursement, Current Procedural Terminology (CPT)^® is the language spoken between providers and payers.

CPT^® refers to a set of medical codes used by physicians, allied health professionals, nonphysician practitioners, hospitals, outpatient facilities, and laboratories to describe the procedures and services they perform.

Specifically, CPT^® codes are used to report procedures and services to federal and private payers for reimbursement of rendered healthcare.

In 1966, the American Medical Association (AMA) created CPT^® codes to standardize reporting of medical, surgical, and diagnostic services and procedures performed in inpatient and outpatient settings. Each CPT^® code represents a written description of a procedure or service, removing the subjective interpretation of precisely what was provided to the patient.

To accommodate the evolving world of healthcare — including the availability of new services and the retirement of outdated procedures, among other considerations — the AMA updates the CPT^® code set annually, releasing new, revised, and deleted codes, as well as changes to CPT^® coding guidelines. The AMA also releases smaller updates to certain sections of the CPT^® code set throughout the year.

The AMA updates CPT^® nomenclature, or medical language, to reflect advances in medicine. Although the AMA owns the copyright to CPT^®, the AMA invites providers and organizations to participate in the ongoing maintenance of the code set, welcoming those who use it to suggest changes to codes and code descriptors.

Recognizing CPT^® Codes

CPT^® codes consist of five characters. Most codes are numeric, but some codes have a fifth alpha character, such as F, T, or U. Examples include:

33275 Transcatheter removal of permanent leadless pacemaker, right ventricular, including imaging guidance (eg, fluoroscopy, venous ultrasound, ventriculography, femoral venography), when performed

3006F Chest X-ray results documented and reviewed (CAP)

0510T Removal of sinus tarsi implant

0079U Comparative DNA analysis using multiple selected single-nucleotide polymorphisms (SNPs), urine and buccal DNA, for specimen identity verification

Understanding Types of CPT^® Codes

Coders assign a code for every service or procedure a provider performs. CPT^® even includes unlisted codes for those services and procedures not specifically named in another defined CPT^® code.

Given the vast number of services and procedures, the AMA has organized CPT^® codes logically, beginning with classifying them into three types:

1. CPT^® Category I: The largest body of codes, consisting of those commonly used by providers to report their services and procedures

2. CPT^® Category II: Supplemental tracking codes used for performance management

3. CPT^® Category III: Temporary codes used to report emerging and experimental services and procedures

Navigating Category I Codes

Most CPT^® codes are Category I codes. These represent existing services or procedures widely used and, when appropriate, approved by the U.S. Food and Drug Administration (FDA).

With a few exceptions, Category I codes, typically denoted by five numeric characters, are arranged in numerical order. One discrepancy to the expected order involves resequenced codes. To give medical coders convenient access to related codes — and thereby help in accurate code selection — the AMA “clusters” similar codes together. A resequenced code comes about when a new code is added to a family of codes, but a sequential number is unavailable.

A second exception to numerical code order involves evaluation and management (E/M) codes. As shown in the Category I code outline below, E/M codes are printed first in CPT^® code books, although they start with the number nine. The AMA chose this order because E/M services are the most often reported healthcare services. This arrangement, as with resequenced codes, is designed for coding efficiency.

The six main sections of CPT^® Category I codes and their sequences are:

1. Evaluation and Management (98000-98016, 99202–99499)

2. Anesthesia (00100–01999, 99100-99140)

3. Surgery (10004–69990) — further broken into smaller groups by body area or system within this code range

4. Radiology (Including Nuclear Medicine and Diagnostic Ultrasound) (70010–79999)

5. Pathology and Laboratory (80047–89398)

6. Medicine (90281–99199, 99500-99607)

Getting Acquainted With Category II Codes

Category II codes, consisting of four numbers and the letter F, are supplemental tracking and performance measurement codes that providers can assign in addition to Category I codes. Unlike Category I codes, Category II codes aren't linked to reimbursement.

Providers use Category II codes — which track specific information about their patients, such as whether they use tobacco — to help deliver better healthcare and achieve better outcomes for patients.

Typically, Category II codes are found directly after the Category I codes in the CPT^® code book. These codes are arranged as follows:

1. Composite Codes (0001F–0015F)

2. Patient Management (0500F–0584F)

3. Patient History (1000F–1505F)

4. Physical Examination (2000F–2060F)

5. Diagnostic/Screening Processes or Results (3006F–3776F)

6. Therapeutic, Preventive, or Other Interventions (4000F–4563F)

7. Follow-up or Other Outcomes (5005F–5250F)

8. Patient Safety (6005F–6150F)

9. Structural Measures (7010F–7025F)

10. Nonmeasure Code Listing (9001F–9007F)

There are also Category II modifiers (1P–8P) that are reported only with Category II codes, when required, and serve as denominator exclusions from the performance measure.

Introducing Category III Codes

Category III codes, depicted with four numbers and the letter T, typically follow Category II codes in the code book. Category III codes are temporary codes that represent new technologies, services, and procedures.

Temporary codes describing new services and procedures can remain in Category III for up to five years. If the services and procedures they represent meet Category I criteria — which include FDA approval, evidence that many providers perform the procedures, and evidence that the procedures have proven effective — they'll be reassigned Category I codes. Conversely, Category III codes can be removed if providers don't use them.

The AMA releases new or revised Category III codes semiannually via their website but publishes the Category III deletions annually with the full set of temporary codes.

Learning How to Use CPT^® Codes

Rules, notes, code descriptors, conventions, guidelines — there’s a lot for new CPT^® coders to digest.

First, procedural coding requires a solid grasp of anatomy and medical terminology. One procedure might have numerous variations, differing only slightly, and selecting the right code will require an ability to comprehend the clinical documentation and code description — to understand what a given procedure is, how the physician performed it, and which code descriptor captures the highest specificity of the procedure performed.

What's more, this knowledge of anatomy and medical terminology must be thorough, as providers can perform services calling for CPT^® codes from any section in the code book. The codes a provider can report aren't limited by the specialty in which they practice. For example, X-ray codes are listed under radiology, but a primary care coder will be required to assign an appropriate X-ray code if the primary care physician interprets an X-ray.

Building Confidence With CPT^® Coding Guidelines

The AMA provides CPT^® coding guidelines that detail when and how to assign codes, which codes can, and can’t be reported together, and other factors critical to compliant coding.

It can't be emphasized enough to review the CPT^® guidelines laid out in each section, subsection, subheading, category, and subcategory before trying to assign codes within that classification.

Equally important, before taking a coding position with the responsibility of determining and reporting CPT^® codes on medical claims, medical coders should consider seeking proper training and credentialing. This is the best way to ensure coding accuracy and optimal reimbursement for employers.

Appending Modifiers to CPT^® Codes

Reporting CPT^® codes requires familiarity with CPT^® modifiers and their use.

A CPT^® modifier consists of two numbers, two letters, or a number and a letter. Many situations require a coder to append modifiers to a CPT^® code to further describe the service or procedure provided. For example, some modifiers show that a procedure was performed on the right side of the body, versus the left side or both sides. Other modifiers indicate that a physician took extra time and effort to perform a service or procedure.

Some people may wonder why a CPT^® code doesn’t include the additional information provided by a modifier. It's because CPT^® code books would be too large and cumbersome if they contained a code for every scenario a coder might encounter. A short list of modifiers goes a long way in expanding the ability to report the unique circumstances of services and procedures performed.

As with CPT^® codes, the AMA creates and annually maintains modifiers for CPT^® coding. Coders will find these modifiers listed in their CPT^® code book. Payers may use modifiers differently, so it’s important to verify each payer’s modifier requirements. And some codes are “exempt” from certain modifiers, which the AMA indicates in the code book.

Relating CPT^® to Other Codes Sets

CPT^® is just one of the many code sets used in healthcare. A few of the other code sets are:

• HCPCS Level II: Used to report procedures, services, supplies, drugs, and equipment

• ICD-10-PCS: Used by facilities to report inpatient procedures (hospitals)

• ICD-10-CM: Used to report diagnoses for patients of inpatient or outpatient providers

Distinguishing the difference between Healthcare Common Procedure Coding System (HCPCS) Level II code use and CPT^® code use can be confusing.

When someone refers to HCPCS (pronounced "hick-picks"), they most likely are referring to the HCPCS Level II code set. HCPCS Level I is the CPT^® code set. The main takeaway is that HCPCS Level II begins where CPT^® ends.

The Centers for Medicare & Medicaid Services (CMS) wanted a classification system for medical supplies, equipment, medications, and services not included in CPT^®, so around 1980 the AMA worked with CMS to develop a new set of codes.

The resulting HCPCS Level II code set was originally used for Medicare patients, but other payers found the codes useful and began requiring providers to use them.

Examples of services, supplies, and items with HCPCS Level II codes include orthotic and prosthetic procedures, hearing and vision services, ambulance services, medical and surgical supplies, drugs, nutrition therapy, and durable medical equipment.

CMS updates the HCPCS Level II code set quarterly, with the largest number of changes often occurring in January.

Establishing Medical Necessity

Payers typically won't reimburse a provider for a claim unless the patient’s diagnosis justifies the service or procedure that the provider performed. This justification is called medical necessity, and this is where the International Classification of Diseases, Tenth Revision, Clinical Modification (ICD-10-CM) coding ties in with CPT^® coding (and HCPCS Level II).

Every claim submitted for reimbursement will include one or more codes, such as a CPT^® code, for the service or procedure, as well as an ICD-10-CM code(s) that reports the patient’s diagnosis to the highest level of specificity.

The ICD-10-CM code (diagnosis) must establish medical necessity for the CPT^® code (service or procedure).

An example of a diagnosis and service meeting medical necessity is when a patient comes into a medical office complaining of stomach pain, and the physician conducts a physical examination. The stomach pain (diagnosis) justifies the reason for the examination (service).

CPT^® Coding Requires Current Code Books

For quick access to a list of CPT^® codes and descriptions, working medical coders typically use software with procedure code lookup, though these tools are also available to students. The key to coding success is staying current and always referencing the code sets that apply to the date of service.

See the full list of CPT^® codes by section.

Last reviewed on March 17, 2025, by the AAPC Thought Leadership Team