Billing code 94729: Diffusing capacity (DLCO)Medicare rate & RVUs

Medicare pays $63.46 for 94729 nationally in the office. Local office rates run $55.18–$88.80.

Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.

What 94729 covers

Diffusing capacity testing evaluates gas transfer from the alveoli into pulmonary capillary blood. In the common single-breath method, the patient inhales a small amount of carbon monoxide with a tracer gas, holds the breath briefly, then exhales into an analyzer. Pulmonologists order it to assess interstitial lung disease, emphysema, pulmonary hypertension, amiodarone toxicity, or fitness for lung resection. Respiratory therapists and PFT technologists perform it in pulmonary offices or hospital labs; a physician interprets the result, sometimes adjusted for hemoglobin.

Report 94729 once per testing session with an eligible primary PFT code, such as spirometry (94010 or 94060), lung volumes (94726 or 94727), oscillometry (94728), bronchospasm provocation (94070), or flow-volume testing (94375). Repeat maneuvers for test quality remain within that unit. Document the measured capacity, test quality, any hemoglobin adjustment, and an interpretation when billing the professional service. CMS pays this add-on within the primary procedure’s global period. Modifier 26 identifies the professional interpretation; modifier TC identifies equipment and staff work. Bill without a component modifier when the same entity provides both components.

This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.

Where 94729 pays more and less

The same RVUs, adjusted for each area’s costs. Open a locality for its calculation, history and nearby areas.

109 of 109 payment localities

94729 rates by state

Office rate range in each state. Select a state to see its payment localities.

How the 94729 rate is calculated

Each of 94729’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.

Payment rules and modifiers for 94729

The CMS indicators that decide how 94729 is paid alongside other services.

What modifiers do to the payment

When to use modifier 26

94729 compared with similar codes

How to choose

94727Lung volumes

94727 uses gas dilution or washout to measure lung volumes; 94729 measures gas transfer into blood with carbon monoxide. Both may be reported when each service is performed.

94726Body plethysmography

94726 measures lung volumes in a body box and may include airway resistance. 94729 measures diffusing capacity and is reported alongside an eligible primary test, not as a substitute.

94010Spirometry

94010 measures airflow and vital capacity by spirometry and can serve as a primary code; 94729 adds a gas-transfer measurement and requires an eligible primary test.

94760N-invas ear/pls oximetry 1

94760 captures a single pulse oximetry determination of oxygen saturation, not the alveolar-capillary gas-transfer measurement obtained with DLCO testing.

Codes related to 94729

Related codes aren’t interchangeable: bill the code that matches the service performed.

Where these rates come from

FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.

CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027

Open CMS sourceHow we calculate rates