CPT 01402: anesthesia for total knee replacement, 7 base units plus time
01402 reports anesthesia for an open or arthroscopic knee joint procedure that includes a total knee replacement. It carries 7 base units in the CMS anesthesia base unit file, and the claim adds actual minutes of anesthesia time.
Written by Salman Saeed, CEO and Co-Founder · Reviewed by a Certified Medical Coder · Last reviewed October 2026In short: 01402 is paid as 7 base units plus time units of 15 minutes, multiplied by a locality conversion factor, with one payment modifier on the line. Postoperative nerve blocks and a second knee in the same session follow their own rules.
What does CPT 01402 report?
01402 reports anesthesia for an open or arthroscopic procedure on the knee joint that includes a total knee replacement. The surgeon's own code for the replacement is 27447. The CMS file lists 01400, other open or arthroscopic knee joint procedures, at 4 base units and diagnostic arthroscopy 01382 at 3.
| Check | What the CMS files show |
|---|---|
| Base units | 7, in the CMS base unit file; CMS states the base units are unchanged for CY 2026 |
| Payment status (RVU26D) | J, anesthesia: no RVUs and no payment amounts in the fee schedule file |
| Global period | XXX |
| MUE | 01402 is not listed in the October 2026 practitioner MUE table |
| 2026 anesthesia conversion factor | $20.49754 national, non-Qualifying APM; $19.42 in Arkansas to $28.15 in Alaska by locality |
Status J means no RVUs, so the allowance is base plus time units multiplied by the locality conversion factor, with one time unit equal to 15 minutes (42 CFR 414.46).
How are anesthesia time units counted for 01402?
Report actual anesthesia minutes in Item 24G of the CMS-1500, converting hours to minutes. The MAC divides them by 15 and rounds to one decimal place.
Anesthesia time starts when the practitioner begins preparing the patient in the operating room or an equivalent area. It ends when the practitioner is no longer furnishing anesthesia and the patient can safely be placed under postoperative care. It does not follow incision or closure.
Chapter 12, section 50E says to report the code with the highest base unit value, with modifier 51, and the total time for all procedures on that line. Payment uses that base value once plus time units from total actual time. The factor is the 2026 Houston locality value.
The same section says to enter the number of surgeries the code applies to when one code covers two or more procedures. Ask your MAC how it wants that count shown beside minutes.
Which payment modifier goes on the 01402 line?
Each Medicare anesthesia line carries one modifier stating who did the work and how it was directed (Chapter 12, sections 50I and 140.3.3). The October 2026 HCPCS file words them as shown.
| Modifier | Billed by | Meaning | Medicare pays |
|---|---|---|---|
| AA | Anesthesiologist | Anesthesia services performed personally | The personally performed rate |
| QY | Anesthesiologist | Medical direction of one CRNA | 50 percent of the physician-alone allowance |
| QK | Anesthesiologist | Medical direction of two, three or four concurrent procedures | 50 percent (42 CFR 414.46) |
| QX | CRNA | CRNA service with medical direction by a physician | A fixed percentage; 50 percent when one CRNA is directed |
| QZ | CRNA | CRNA service without medical direction | The CRNA allowance, which may not exceed the physician-alone allowance |
When it is medically necessary for both a CRNA and an anesthesiologist to be completely involved, section 140.4.2 allows full payment to each, with AA and QZ, and both must submit documentation. GC is added, with a payment modifier, when a resident took part under a teaching anesthesiologist. More is in anesthesia billing.
Can I bill a nerve block with 01402?
Sometimes. Postoperative pain management is part of the surgeon's global package, and the surgeon may ask anesthesia to take it over when it needs techniques beyond the surgeon's experience. NCCI Chapter II allows a peripheral nerve block (64400 to 64530) on the day of surgery for postoperative pain only if the operative anesthetic is general, subarachnoid or epidural and its adequacy does not depend on the block.
Modifier 59 or XU shows the block was for postoperative pain, and a procedure note belongs in the record. A block used as the primary anesthetic or a supplement to it is not separately reportable, and a catheter placed for continuous infusion for intraoperative pain is part of the anesthesia code.
How does 01402 appear on the claim?
Item 24D carries 01402 with the payment modifier, up to four modifiers fit, and Item 24G carries the minutes. If the surgeon furnishes the anesthesia, Medicare does not pay it separately: NCCI Chapter II includes it in the surgical payment, under OPPS as well.
How are minutes and modifiers entered for 01402?
A knee replacement anesthesia line is long, so the minutes field decides whether it is right. Item 24G holds elapsed minutes, hours converted per Chapter 26, and Item 24D holds 01402 with the payment modifier and up to three more modifiers. Item 24E points to the joint diagnosis, usually osteoarthritis of the knee, in Item 21.
RVU26D lists 01402 as status J with no RVUs or payment amounts, and the practitioner MUE table has no row for it. A claim with a missing start or end time cannot be priced from the chart, so the anesthesia record is the control document.
Example: Induction begins at 7:40 and the patient leaves the operating room at 10:25 on 10/15, 165 minutes. The line reads 01402, modifier QK, pointer A (M17.11), 165 in Item 24G, $1,380.00. Entering 2.75 instead of 165 would not match the minutes in the anesthesia record.
Why is 01402 denied or reduced?
| Code | What X12 says | What usually causes it |
|---|---|---|
| CARC 4 | The procedure code is inconsistent with the modifier used | No payment modifier, or QX or QZ on a physician claim |
| CARC 59 | Processed based on multiple or concurrent procedure rules (for example concurrent anesthesia) | A QK or QY line paid at the medically directed rate |
| CARC 97 | The benefit for this service is included in the payment/allowance for another service/procedure that has already been adjudicated | A block the anesthesia code already includes |
| CARC 197 | Precertification/authorization/notification/pre-treatment absent | The knee surgery was denied for authorization and the anesthesia line follows it |
If these denials keep coming back, our denial management team can work them. Endoscopy anesthesia: 00731, 00811.
Related codes
- Physician Fee Schedule relative value files, RVU26D (October 2026) · CMS
- CY 2022 Anesthesia Base Units by CPT code (unchanged for CY 2026) · CMS
- Anesthesiologists Center: anesthesia base units and conversion factors · CMS
- Medicare NCCI Medically Unlikely Edits, practitioner services table, effective 10-01-2026 · CMS
- 2026 NCCI Medicare Policy Manual, all chapters (revision 1/1/2026) · CMS
- Medicare Claims Processing Manual, Chapter 12: Physicians/Nonphysician Practitioners · CMS
- Medicare Claims Processing Manual, Chapter 26: Completing and Processing Form CMS-1500 Data Set · CMS
- 42 CFR 414.46: Additional rules for payment of anesthesia services · eCFR
- HCPCS quarterly update, October 2026 alpha-numeric file · CMS
- Claim Adjustment Reason Codes · X12
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Common questions
Straight answers from the team that does the work.
Ask a billing lead directly. A 20-minute call, Monday to Friday, 9am to 5pm Eastern.
01How are anesthesia time units counted for 01402?
Report the actual anesthesia minutes in Item 24G. The MAC divides the minutes by 15 and rounds to one decimal place. Time runs from the start of preparing the patient in the operating room to the point the patient can safely be placed under postoperative care, not from incision.
02How many base units does 01402 carry?
Seven. The CMS anesthesia base unit file lists 7 for 01402, and the CMS Anesthesiologists Center page states the base units are unchanged for CY 2026. Other knee codes are lower, such as 4 for 01400, and status J means units drive payment.
03How do I bill anesthesia for two knees in one session?
Chapter 12, section 50E says to report the anesthesia code with the highest base unit value with modifier 51 and the total time for all procedures on that line. Payment is the highest base unit value once plus time units from the actual total time.
04Which modifier goes with a CRNA under medical direction?
The CRNA reports QX. The anesthesiologist reports QY when directing one CRNA or QK when directing two, three or four concurrent cases. With one directed CRNA, Chapter 12 section 140.4.2 pays each 50 percent of the allowance for the physician working alone.
05Does Medicare pay for anesthesia given by the surgeon?
Not separately. With limited exceptions, NCCI Chapter II says Medicare does not allow separate payment for anesthesia furnished by the physician who also performs the surgery, because it is included in the surgical payment. OPPS works the same way, so the surgeon cannot bill it.
Anesthesia claims paid below the units?
We check minutes, base units and the payment modifier against the case record before the claim goes out.