Anesthesia CPT Codes
Anesthesia billing works unlike any other specialty: payment isn't a flat fee per code but a formula of base units plus time units, multiplied by an anesthesia-specific conversion factor. The code sets the base units by body area, the clock sets the time units, and a stack of modifiers describes who did the work and how sick the patient was. It's the one corner of CPT where the arithmetic is the billing.
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Anesthesia CPT codes
Anesthesia, Lower Intestinal Endoscopy
Anesthesia for colonoscopy and lower GI procedures. Screening colonoscopy anesthesia is 00812.
Anesthesia, Intraperitoneal Procedures, Lower Abdomen
Covers common laparoscopic lower-abdominal surgery.
Anesthesia, Total Knee Arthroplasty
Anesthesia for knee replacement procedures.
Anesthesia, Labor Epidural
Neuraxial labor analgesia. Cesarean conversion adds 01968 as an add-on.
Anesthesia, Salivary Gland Procedures
First code of the anesthesia section, head region.
Qualifying Circumstances: Extreme Age (Add-on)
Anesthesia add-on for patients under 1 or over 70. Payer acceptance varies.
Codes in blue have full detail pages with documentation requirements, billing mistakes, and FAQ.
Anesthesia billing notes
Payment = (base units + time units) × the anesthesia conversion factor. Each code in 00100–01999 carries fixed base units reflecting the procedure's complexity; time units accrue in 15-minute increments.
Anesthesia time starts when the provider begins preparing the patient and ends when the patient is safely transferred to post-anesthesia care. Document start and stop to the minute.
Delivery modifiers are mandatory: AA for personally performed by the anesthesiologist, QZ for CRNA without medical direction, QY/QK/QX for the medical-direction combinations. The modifier determines who gets paid what percentage.
Physical status modifiers P1 through P6 describe patient condition. P3 and above add units with some payers, and they must match the pre-anesthesia assessment.
Qualifying circumstances add-ons exist for extremes: 99100 for very young or very old patients, 99140 for emergencies. Payer acceptance varies, but the codes exist to claim the added risk.
Frequently asked questions about anesthesia billing
How is anesthesia payment actually calculated?▼
Base units plus time units, times the anesthesia conversion factor. The code fixes the base units (a knee replacement carries more than a colonoscopy), time accrues in 15-minute units from preparation to handoff, and the conversion factor is a dollar figure payers set separately from regular RVU pricing.
What do modifiers AA and QZ mean?▼
Who provided the anesthesia. AA means the anesthesiologist personally performed the case and typically pays 100%. QZ means a CRNA worked without medical direction. The QY/QK/QX set covers medical-direction arrangements, splitting payment between physician and CRNA. Claims without a delivery modifier don't pay.
When does anesthesia time start and stop?▼
It starts when the anesthesia provider begins preparing the patient for induction, usually in the OR or immediately before, and stops when the patient is safely handed to PACU staff. It's not scheduled OR time or surgical time, and the minutes must be documented, because every 15 of them is a payable unit.
Sources
- Code set structure and updates: American Medical Association — CPT
- Fee schedule and component billing rules: CMS Medicare Physician Fee Schedule
- How we research and verify: our editorial policy
CPT® is a registered trademark of the American Medical Association. Content on this page is original educational writing, not a reproduction of AMA-copyrighted descriptions. Verify codes and payer rules before billing.