The Evolution of CPT Codes and Their Emergence as THE National Healthcare Billing Standard

Part of Nurse.org’s Nursing AI Watch, our ongoing investigation into how artificial intelligence is reshaping nursing practice. In this contributor piece, nurse leader Stephanie Witwer explains how we got here: how a billing language created in 1966 became the standard that decides what counts as healthcare work, and why nursing was never written into it.

For more than half a century, the U.S. health system has relied on one dominant language to describe, measure, and pay for clinical work: Current Procedural Terminology, or CPT. CPT codes are so embedded in our national infrastructure that most clinicians never stop to question them. But for nursing, and especially ambulatory care nursing, CPT is not just a billing system. It is a structural barrier that determines whether our work is visible, measurable, and valued.

Understanding how CPT evolved, and why it excludes nursing, is essential to understanding why RN practice remains undervalued today.

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CPT was created by the American Medical Association (AMA) in 1966 in response to the introduction of third-party payment systems. It was clear that payment needed to be based on national service descriptors, and a system was needed to “price” each service. Its purpose was clear:

• Create a uniform national language
• Support documentation and billing
• Enable claims processing
• Facilitate research, guideline development, and utilization review

From the beginning, the CPT coding system was designed for and by physicians, with full ownership and control resting with the AMA.

Milestones in CPT’s Adoption as the National Billing Standard

Through a series of regulations passed between 1983 and 2009, CPT codes became increasingly embedded in the payment systems of Medicare and all other payers. In 2000, their use was mandated; this mandate was further reinforced as electronic billing became required. Today, CPT contains more than 11,000 codes and expands annually. It is a sophisticated system maintained and evolved by the AMA, and it forms the basis for annual updates to CMS’s Physician Fee Schedule.

The AMA’s Relative Value Scale Update Committee (RUC) recommends the relative value units, or RVUs, assigned to CPT codes. RVUs determine how much a service is “worth” in the Medicare Physician Fee Schedule and in most productivity models across the country.

RVUs are built from three components:

• Work (roughly 52%) — decision making, time, skill, effort, stress, risk
• Practice expense (42–44%) — clinical labor, supplies, equipment, overhead
• Malpractice expense (4–6%) — liability and risk

RN labor falls under practice expense, not work. That means RN contributions are treated as overhead, a cost to be minimized, rather than as clinical value. And RNs are grouped into a category called “clinical” or “auxiliary” staff alongside a wide range of licensed and unlicensed personnel — think receptionist or medical assistant.

The values of CPT codes are assessed primarily by surveying the physicians and others providing the services, without rigorous external validation. CMS has historically adopted roughly 90% of RUC recommendations. The result is a national valuation system built almost entirely on physician-centric perspectives.

Notably, even CMS is losing confidence in this system. In its proposed 2027 payment rule, the agency calls the AMA surveys behind those values outdated and “ultimately unreliable,” and proposes to phase them out in favor of cost data it can actually verify. Then it goes further. In a formal request for input, CMS asks openly whether Medicare should keep relying on CPT and the RUC at all, pointing out that no law requires it, and that its own advisors have warned for twenty years that the process is run by the specialties with a financial stake in the results. The valuation system nursing has been invisible inside for sixty years is being questioned by the very agency that pays the bills. Comments on that question are open to anyone through September 14, 2026.

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Because CPT codes were never designed for nurses, RNs have almost no direct billing authority. We may enter select codes, but billing is attributed to the supervising physician or qualified health care professional (QHP). No CPT codes exist specifically for RN-delivered services.

The most common example is CPT code 99211, often used for RN visits. It carries extremely low value because the code assumes no medical decision making — and the work component, where decision making lives, drives over half of a code’s value. The same code is used for a 10-minute blood pressure check and a 45-minute complex education visit. No detail about the RN’s service is captured. No differentiation. No recognition.

And the RVUs flow to the supervising physician, not the RN.

In health care, what is not paid for is treated as expense. And expenses are minimized.

When RN work is invisible in CPT, it becomes invisible in RVUs. When it is invisible in RVUs, it becomes invisible in productivity models. When it is invisible in productivity models, it becomes invisible in compensation, staffing, budgeting, and strategic planning.

This is not a documentation problem. It is a structural problem.

Without CPT codes for RN services, we cannot:

• Describe RN practice in standardized terms
• Link RN interventions to outcomes
• Quantify the cost of delivering RN care
• Demonstrate RN practice at the top of scope
• Build a foundation for RN billing
• Make nursing visible in national policy

CPT was created to standardize medical services, support billing, assign value, and enable research. Nursing needs the same foundation — not to mimic medicine, but to articulate the unique, evidence-based, relationship-centered work that nurses perform.

Until nursing has a standardized taxonomy and a pathway to valuation, RN work will remain structurally invisible in the systems that determine value.

The stakes of that invisibility are rising fast: the AMA is now building billing codes for clinical AI, and Medicare has proposed its first payment category for software. Meanwhile, nursing remains an overhead expense. Part two of this series will look at what nursing can build instead.

🤔 Think about your last shift: what’s one thing you did that changed a patient’s outcome but never appeared anywhere on a bill? Tell us about it in the comments below.

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