Anesthesia CPT codes run from 00100 to 01999, and you select them by the surgical procedure performed, not by the type of anesthesia given. Payment follows a formula no other CPT section uses: base units plus time units plus modifying units, multiplied by the payer’s conversion factor. For 2026, Medicare set that factor at $20.4976.
Three code families turn up on anesthesia claims. Anesthesia services run 00100 to 01999. Qualifying circumstances run 99100 to 99140 as add-on codes. Moderate sedation runs 99151 to 99157 and sits in a different section of CPT entirely. The coding team behind ClaimMax RCM medical billing maintains this guide against current CMS and AMA source documents.
This guide covers the crosswalk from a surgical code to its anesthesia code, the payment formula with both 2026 conversion factors, all 10 modifiers and when each applies, what Medicare pays on qualifying circumstances, and the retired codes that still haven’t come out of published cheat sheets.
What are anesthesia CPT codes?
There’s no CPT code for general anesthesia. None exists. Anesthesia CPT codes describe the surgical procedure and the body region, not the anesthetic technique. General anesthesia, regional blocks, and monitored anesthesia care all get reported under the same code for the same surgery. The technique reaches the payer through modifiers.
Why the anesthesia type doesn’t change the code
A coder who reads “general endotracheal anesthesia” in the chart and goes hunting for a code that says so won’t find one. Start with the surgical procedure instead. Map to the anesthesia code from there.
The same rule ends the search for a spinal anesthesia code. There’s no CPT code for spinal or regional anesthesia. Both fall under the anatomic code for whatever surgery the patient had that day.
Modifiers carry the technique. QS flags monitored anesthesia care. The provider role modifiers AA, QK, QX, QY, QZ, and AD tell the payer who delivered the anesthetic and under what level of supervision. The ASA anesthesia modifier guidance publishes the full descriptors.
What the anesthesia code already includes
Anesthesia codes bundle more than most billers expect. Per CMS NCCI Chapter 2, the anesthesia service already covers the pre-anesthetic evaluation, administration of anesthetics and fluids, monitoring of physiologic parameters, and the usual supportive services. Bill any of those on a separate line and you’ll see a bundling denial.
One more CMS rule belongs here. For Medicare, you report one anesthesia code per case unless the code is an add-on. Practices that submit two anesthesia codes for a single session get one of them kicked back.
That’s the purpose of anesthesia CPT codes in a nutshell: one code, one anatomic region, one payment calculation. Pick the code from the anesthetic technique and the mismatch surfaces as a denial weeks later, not at submission.
Which CPT code ranges cover anesthesia?
Anesthesia CPT codes are organized by body area, running head to foot from 00100 through 01860, then by service type: 01916 to 01942 for radiological procedures, 01951 to 01953 for burn debridement, 01958 to 01969 for obstetric anesthesia, and 01990 to 01999 for other services. Unlisted procedures use 01999.
Anesthesia code ranges by body area
Keep this table where your coders can reach it. Most anesthesia coding cheat sheets stop at the code range. The third column names the procedures that drive volume in each band, which is what a coder needs when scanning.
| Area of the Body | Code Range | What it covers |
|---|---|---|
| Head | 00100-00222 | Eye, ear, nose, intraoral, cranial, facial bone |
| Neck | 00300-00352 | Thyroid, larynx, trachea, neck vessels |
| Thorax (chest wall and shoulder girdle) | 00400-00474 | Skin, breast, clavicle, scapula, ribs |
| Intrathoracic | 00500-00580 | Heart, lungs, esophagus, pacemaker, transplant |
| Spine and spinal cord | 00600-00670 | Cervical, thoracic, lumbar, extensive spine |
| Upper abdomen | 00700-00797 | Liver, gallbladder, stomach, upper GI endoscopy |
| Lower abdomen | 00800-00882 | Colonoscopy, hernia, kidney, bladder, pelvis |
| Perineum | 00902-00952 | Anorectal, prostate, vaginal, urologic |
| Pelvis (except hip) | 01112-01173 | Bone aspiration, pelvic tumor, pelvic fracture |
| Upper leg (except knee) | 01200-01274 | Hip joint, femur, hip arthroplasty |
| Knee and popliteal area | 01320-01444 | Knee arthroscopy, knee arthroplasty, knee vessels |
| Lower leg (below knee, including ankle and foot) | 01462-01522 | Ankle, foot, lower leg bones and vessels |
| Shoulder and axilla | 01610-01680 | Shoulder joint, shoulder arthroplasty |
| Upper arm and elbow | 01710-01782 | Humerus, elbow, upper arm vessels |
| Forearm, wrist and hand | 01810-01860 | Wrist, hand, distal radius and ulna |
| Radiological procedure | 01916-01942 | Arteriography, CT, MRI, image-guided spine injection |
| Burn excisions or debridement | 01951-01953 | Reported by percentage of body surface |
| Obstetric | 01958-01969 | Labor analgesia, vaginal delivery, cesarean |
| Other procedure | 01990-01999 | Nerve blocks, epidural management, unlisted |
Table 1. Anesthesia CPT code ranges by body area. Source: AMA CPT code set, CMS NCCI Policy Manual Chapter 2.
The three code families you bill from
Anesthesiology CPT codes get discussed as one block, and that costs practices money. CMS NCCI names three separate families, and they don’t behave the same way on a claim.
- 00100 to 01999 covers anesthesia services and pays on the unit formula.
- 99100 to 99140 covers qualifying circumstances and reports as add-on codes only.
- 99151 to 99157 covers moderate sedation and belongs to the Medicine section of CPT.
That third family isn’t anesthesia. Moderate sedation carries different provider rules, different documentation, and a different payment method. Mixing the two produces some of the messiest anesthesia billing codes problems we see on new accounts.
Unlisted procedures fall to 01999. Use it when no specific code describes the service, and expect manual review with slower adjudication on those claims.
How do you find the anesthesia code for a surgical procedure?
Start with the surgical CPT code, not the anesthesia record. Look that surgical code up in the ASA Crosswalk, which maps every surgical CPT code to the anesthesia code or codes reportable with it. The anesthesia code follows the surgery. Choosing it from the anesthetic technique is the most common source of code mismatch denials.
What the ASA Crosswalk does
The American Society of Anesthesiologists publishes the Crosswalk every year. It answers the question billers ask most often: what is the anesthesia code for a cholecystectomy, an appendectomy, a knee replacement. That’s the whole job of the document.
The ASA Crosswalk maps surgical CPT to anesthesia codes, and one surgical code can point to more than one anesthesia code. The operative report settles it. A procedure code for anesthesia that came off the schedule instead of the op note will hold up until someone audits it.
Surgical CPT to anesthesia CPT for 20 high-volume procedures
| Surgical Procedure | Anesthesia CPT | When it changes |
|---|---|---|
| Cholecystectomy, open or laparoscopic | 00790 | Intraperitoneal upper abdomen, not otherwise specified |
| Appendectomy | 00840 | Intraperitoneal lower abdomen, not otherwise specified |
| Screening colonoscopy | 00812 | 00811 when the scope is diagnostic or therapeutic |
| Combined upper and lower GI endoscopy | 00813 | Both scopes in a single session |
| Upper GI endoscopy (EGD) | 00731 | 00732 for ERCP |
| Total knee arthroplasty | 01402 | 01400 for other knee joint procedures |
| Total hip arthroplasty | 01214 | 01212 for hip disarticulation |
| Cataract or lens surgery | 00142 | 00140 for other eye procedures |
| Cesarean delivery | 01961 | 01968 following neuraxial labor analgesia |
| Vaginal delivery with labor epidural | 01967 | 01969 if cesarean hysterectomy follows |
| Lumbar spine surgery | 00630 | 00670 for extensive spine and cord procedures |
| Cervical spine surgery | 00600 | 00604 in the sitting position |
| Shoulder arthroplasty | 01630 | 01620 for closed shoulder procedures |
| Intraoral surgery | 00170 | 00174 for pharyngeal procedures |
| CT or MRI under anesthesia | 01922 | 01916 for diagnostic arteriography |
| Lumbar or sacral image-guided spine injection | 01938 | 01937 for cervical or thoracic |
| Forearm, wrist, or hand soft tissue | 01810 | 01820 for closed procedures on bone |
| Radical hysterectomy | 00846 | 00944 for vaginal hysterectomy |
| Hernia repair, lower abdomen | 00830 | 00832 for ventral and incisional repair |
| Burn excision or debridement | 01951-01953 | Selected by percentage of body surface treated |
Table 2. Surgical procedure to anesthesia CPT crosswalk for high-volume procedures. Confirm every mapping against the current ASA Crosswalk edition before submission. Source: AMA CPT code set, ASA Crosswalk.
Where the crosswalk breaks
Three situations send a clean mapping from surgical codes to anesthesia CPT codes sideways, and your coders will hit all three this month.
A single surgical code sometimes maps to several anesthesia codes. The operative report decides which one, and the surgery schedule doesn’t get a vote. Pull the op note before the claim goes out.
Converted procedures change the answer mid-case. A laparoscopic approach that opens partway through moves the anesthesia code with it. The difference between anesthesia CPT codes and surgical CPT codes shows up here: the surgeon bills what was done, and you bill the anatomic region where the anesthetic was managed.
Multiple procedures in one session collapse to one code. For Medicare, report the anesthesia code carrying the highest base unit value unless the code is an add-on. Automated payer edits check the surgeon’s CPT against yours, so a mismatch denies without a human ever reading the claim.
What are anesthesia base units?
Base units are a fixed value assigned to each anesthesia CPT code, reflecting the complexity and risk of the procedure rather than how long it takes. CMS publishes them annually in the anesthesia base unit file. For 2026, CMS confirmed base units are unchanged across the 00100 to 01999 range.
You can pull the complete list from the CMS Anesthesiologists Information Center, which posts the base unit file alongside the annual conversion factors. The four codes below show how far the scale stretches.
Anesthesia base units by CPT code
| CPT Code | Descriptor | Base Units | What drives the value |
|---|---|---|---|
| 00400 | Anesthesia for procedures on the thorax, chest wall and shoulder girdle | 3 | Superficial site, low physiologic burden |
| 00700 | Anesthesia for upper abdominal wall procedures | 4 | Abdominal access, moderate complexity |
| 00100 | Anesthesia for procedures on salivary glands | 5 | Airway proximity raises the floor |
| 00561 | Anesthesia for heart surgery with pump oxygenator, patient under 1 year | 15 | Pediatric cardiac, highest acuity band |
Table 3. Anesthesia base unit anchor values, CY 2026. Base units for the full 00100 to 01999 range are published in the CMS anesthesia base unit file. Confirm every value against that file before loading a charge master. Source: CMS anesthesia base unit file, Anesthesiologists Information Center.
Base units on anesthesia CPT codes don’t move. Not with case length, not with patient status, not with who delivered the anesthetic. Those three variables live elsewhere in the formula, and keeping them separate in your head prevents most anesthesia cpt calculation errors.
Why the wrong code costs more than the wrong time
Time errors move a claim by fractions of a unit. Code errors move it by the whole base unit value, on every single case coded that way.
Run the arithmetic on a cardiac case. The gap between a 3-unit code and a 15-unit code is 12 units before anyone starts a clock. Multiply that by a conversion factor and by a year of volume, and the crosswalk stops looking like a clerical detail.
Base unit errors are systematic. They repeat across every case your team codes the same way, which is what turns a coding habit into a recoupment exposure. Auditors find these fast because the pattern is identical claim after claim.
How are anesthesia time units calculated?
One anesthesia time unit equals 15 minutes. CMS requires the actual anesthesia time in minutes on the claim, then computes time units by dividing reported minutes by 15 and rounding to one decimal place. That means 117 minutes reports as 7.8 time units, not 8. Never round the documented minutes themselves.
When anesthesia time starts and stops
Time on anesthesia CPT codes 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 services and the patient can be safely placed under postoperative care.
Surgical time doesn’t enter into it. Incision to closure is the surgeon’s number. Your anesthesia time units start earlier and usually finish later, and billing the surgeon’s clock is one of the quietest ways to underbill a whole case list.
Increments vary by contract. Most payers use 15-minute increments, and some commercial contracts and state Medicaid programs work in 10-minute increments instead. Check the contract before you build the rule into your system.
The rounding rule most guides get wrong
Several published guides round anesthesia time units to whole numbers. CMS doesn’t. The federal anesthesia base unit and time rules carry the same one-decimal standard. Watch what the difference does across a case list.
| Anesthesia Minutes | Time Units | Note |
|---|---|---|
| 30 | 2.0 | Clean multiple of 15 |
| 45 | 3.0 | Clean multiple of 15 |
| 47 | 3.1 | Rounding to 3 costs 0.1 unit |
| 90 | 6.0 | Clean multiple of 15 |
| 117 | 7.8 | Rounding to 8 overbills by 0.2 unit |
| 120 | 8.0 | Clean multiple of 15 |
| 163 | 10.9 | Rounding to 11 overbills by 0.1 unit |
| 180 | 12.0 | Clean multiple of 15 |
Table 4. Anesthesia time unit conversion at 15-minute increments. Source: Medicare Claims Processing Manual, Pub. 100-04, Chapter 12.
Rounding down leaves money behind. Rounding up creates an overpayment you’ll return with interest. Neither one is a rounding preference, and both show up in the same audit sample.
Interruptions and discontinuous time
CMS treats anesthesia time as a continuous period and allows blocks around interruptions when the practitioner furnishes continuous anesthesia care around the break. The anesthesia record has to show those blocks. A single start time and a single stop time won’t support a case that had a gap in the middle.
Documentation is where anesthesia coding gets audited hardest. A 2025 HHS-OIG audit identified $45.7 million in at-risk anesthesia payments, with 20 of 28 sampled sessions lacking documentation adequate to support the billed service. That’s a records problem, not a coding problem, and the medical billing service team catches it at the scrubber rather than at the appeal.
If your time entries come off an AIMS export and nobody reconciles them against the anesthesia record before submission, that gap is worth a look. ClaimMax RCM can pull a 90-day sample.
What are modifying units in anesthesia billing?
Modifying units are the third component of payment on anesthesia CPT codes. They come from two sources: ASA physical status modifiers P1 through P6, which describe the patient’s condition before anesthesia, and qualifying circumstances add-on codes +99100, +99116, +99135, and +99140, which describe conditions that make the case harder to manage.
ASA physical status modifiers P1 to P6
The ASA physical status modifiers P1 to P6 definitions describe the patient, not the procedure. Assign them from the pre-anesthesia evaluation.
| Modifier | ASA Physical Status | Modifying Units | Documentation required |
|---|---|---|---|
| P1 | Normal healthy patient | 0 | Pre-anesthesia evaluation showing no systemic disease |
| P2 | Mild systemic disease | 0 | Named condition, controlled, in the pre-op assessment |
| P3 | Severe systemic disease | 1 | Specific diagnosis and severity, not the label alone |
| P4 | Severe systemic disease, constant threat to life | 2 | Clinical findings supporting constant threat |
| P5 | Moribund patient not expected to survive without the operation | 3 | Documented prognosis without intervention |
| P6 | Declared brain-dead patient, organ donor | 0 | Declaration of brain death in the record |
Table 5. ASA physical status modifiers and modifying unit values. Unit recognition varies by payer contract. Source: ASA Relative Value Guide, CMS Medicare Physician Fee Schedule.
Two compliance points sit behind that table. The physical status modifier reflects the pre-anesthesia evaluation, not how the case turned out. And assigning modifier P3 or above without supporting clinical documentation is an audit exposure, because reviewers cross-reference the assignment against the pre-operative assessment.
Emergency cases take an E suffix. A P3 patient in an emergency reports as P3E. Payment effect varies by payer, and the suffix belongs in the record regardless of whether your contract pays for it.
Qualifying circumstances add-on codes
How many qualifying circumstances codes are there? Four. They report in addition to the primary anesthesia code and never stand alone.
| Code | Condition | Units | Documentation required |
|---|---|---|---|
| +99100 | Patient of extreme age, under 1 year or over 70 years | 1 | Exact age confirmed in the pre-anesthesia assessment |
| +99116 | Anesthesia complicated by total body hypothermia | 5 | Intraoperative temperature record |
| +99135 | Anesthesia complicated by controlled hypotension | 5 | Intraoperative blood pressure log |
| +99140 | Anesthesia complicated by emergency conditions | 2 | Statement of the emergent indication in the operative note |
Table 6. Anesthesia qualifying circumstances add-on codes. Unit values reflect the ASA Relative Value Guide; payer recognition varies. Source: AMA CPT code set, ASA Relative Value Guide.
Three details separate a clean qualifying circumstances claim from a denied one. The +99100 upper age threshold applies to patients older than 70 years and one day on the date of the procedure, so a patient on their 70th birthday doesn’t qualify.
Codes +99116 and +99135 don’t get reported with cardiac procedures performed on cardiopulmonary bypass, where the hypothermia or hypotension results from the bypass itself. The complication has to be something the anesthesia team induced and managed.
The emergency definition behind +99140 is narrow. An emergency exists when delay in treatment would lead to a significant increase in the threat to life or body part. An unscheduled add-on case doesn’t meet that bar on its own, and the 99140 CPT code description won’t rescue a claim the operative note can’t support.
When more than one qualifying circumstance applies
You can report more than one qualifying circumstance code on a single case when the clinical conditions support each one. An 82-year-old brought in as an emergency carries both +99100 and +99140, and both belong on the claim.
Medicare handles these codes differently from commercial payers, and the difference catches practices every year. That comparison sits a few sections down.
How is anesthesia payment calculated?
Anesthesia payment uses a formula no other CPT section uses: base units plus time units plus modifying units, multiplied by the conversion factor. Written out, that’s (B + T + M) x CF. Standard CPT codes pay on relative value units. Anesthesia doesn’t, which is why cpt code anesthesia claims price differently from every other line your practice submits.
The anesthesia payment formula
Four variables, and each one comes from a different place. B is fixed by the code you selected. T is documented minutes divided by 15, carried to one decimal. M comes from physical status and qualifying circumstances. CF is the dollar value per unit, set by CMS for Medicare and by contract for everyone else.
Medical direction changes the arithmetic. On a medically directed case, the anesthesiologist and the CRNA are each paid on 50 percent of the sum of base and time units, multiplied by the applicable locality conversion factor. Anesthesia coding is based on a billing formula that splits, and billing systems that miss the split underpay both providers.
Verify your own numbers against the Medicare physician fee schedule rather than a published national average, because locality adjustment moves the figure your claims post against.
A worked example: total knee arthroplasty
Take a total knee arthroplasty under CPT 01402. The patient is 68 with controlled diabetes and a BMI of 36, assigned P3. Anesthesia time runs 95 minutes. Pull the base unit value for 01402 from the CMS file; for this walkthrough, assume it comes back as 7.
| Component | Input | Result |
|---|---|---|
| Base units | CPT 01402, from the CMS base unit file | 7.0 |
| Time units | 95 minutes divided by 15, one decimal | 6.3 |
| Modifying units | Physical status P3 | 1.0 |
| Total units | 7.0 + 6.3 + 1.0 | 14.3 |
| Medicare non-QP | 14.3 units x $20.4976 | $293.12 |
| Commercial example | 14.3 units x $75.00 (illustrative rate) | $1,072.50 |
Table 7. Anesthesia payment calculation walkthrough. Base unit input is illustrative and must be confirmed against the CMS anesthesia base unit file. The commercial conversion factor shown is illustrative; contract rates vary. Source: CMS CY 2026 Physician Fee Schedule final rule.
The gap between those two columns is the reason payer mix drives anesthesia revenue more than case volume does. Same case, same documentation, and the allowed amount moves by a factor of three.
What every anesthesia claim must carry
CMS asks for three things on an anesthesia claim, and all anesthesia codes must include each one.
- The anesthesia CPT code that describes the service.
- The actual anesthesia time in minutes, not the calculated units.
- Exactly one payment modifier, plus any informational modifiers that apply.
Miss the third item and the claim doesn’t price. Submit two payment modifiers and it denies. That rule alone is worth checking against your scrubber this week.
What is the 2026 anesthesia conversion factor?
CMS finalized two anesthesia conversion factors for 2026. The non-qualifying APM rate is $20.4976 per unit and the qualifying APM rate is $20.5998. Both took effect January 1, 2026 under the CY 2026 Physician Fee Schedule final rule, CMS-1832-F. Both are national figures before locality adjustment.
The two 2026 anesthesia conversion factors
Compare that against last year. The 2025 anesthesia conversion factor was $20.3178, a single rate covering everyone. The 2026 non-APM figure represents a 0.88 percent update and the qualifying APM figure a 1.39 percent update, per the ASA payment policy alert issued when the rule dropped.
Verify both figures against the Noridian anesthesia conversion factors file, which your Medicare Administrative Contractor publishes with locality detail.
One 2026 change works in your favor and almost nobody covers it. CMS finalized a 2.5 percent efficiency adjustment to work relative value units for the year, and time-based codes are excluded from it. Anesthesia sits outside that cut.
Why there are suddenly two rates
2026 is the first year CMS applies separate conversion factors tied to Advanced Alternative Payment Model participation. Before this year, one number covered every anesthesiologist and every CRNA in the country.
A billing system that doesn’t differentiate by APM status prices every claim against one rate. If your group has qualifying APM participants, that’s a systematic underpayment across every case they touch, and it never shows up as a denial. It shows up as a variance nobody is looking for, which is where underpayment flagging at posting earns its keep.
What the national figure doesn’t tell you
The national conversion factor isn’t the rate you get paid. CMS publishes locality-adjusted anesthesia conversion factor files separately, and the number that posts against your claims depends on where you practice.
Commercial conversion factors are a different conversation entirely. They’re set by contract and generally run well above the Medicare figure. If your last renewal happened without anyone opening the fee schedule, a payer contract rate review is the fastest place to find money in an anesthesia CPT codes workflow.
Practices with qualifying APM participants and a single fee schedule entry get underpaid on every case, and it never surfaces as a denial. That’s the kind of variance a posting-stage review catches.
Which anesthesia modifiers do you use?
Every anesthesia claim carries exactly one payment modifier. AA covers a case the anesthesiologist personally performed. QK, QY, and AD cover medical direction and supervision. QX and QZ get reported by the CRNA. QS, G8, G9, and GC are informational and never replace the payment modifier.
Anesthesia payment modifiers
Most published anesthesia modifiers list content stops at the descriptor and never connects the modifier back to the anesthesia CPT codes it prices. The column that matters on a Tuesday afternoon is the last one.
| Modifier | Who reports it | When it applies | Payment effect |
|---|---|---|---|
| AA | Anesthesiologist | Personally performed, present for the entire case | Full allowable |
| AD | Anesthesiologist | Medical supervision of more than 4 concurrent procedures | Reduced, supervision rate |
| QK | Anesthesiologist | Medical direction of 2, 3, or 4 concurrent procedures | 50 percent of base plus time units |
| QY | Anesthesiologist | Medical direction of one qualified nonphysician anesthetist | 50 percent of base plus time units |
| QX | CRNA or AA | Nonphysician anesthetist service with medical direction | 50 percent of base plus time units |
| QZ | CRNA | Nonphysician anesthetist service without medical direction | Full allowable |
| QS | Either | Monitored anesthesia care | Informational, no payment effect alone |
| G8 | Either | MAC for a deep, complex, or markedly invasive procedure | Informational |
| G9 | Either | MAC for a patient with severe cardiopulmonary history | Informational |
| GC | Teaching physician | Service performed in part by a resident under direction | Informational, payment modifier still required |
Table 8. Anesthesia payment and informational modifiers. Payment effects reflect Medicare policy; commercial recognition varies by contract. Source: Medicare Claims Processing Manual, Pub. 100-04, Chapter 12.
Two scenarios pay at the full allowable. AA applies when the anesthesiologist handles the case alone. QZ applies when a CRNA practices without physician medical direction, in states and settings that permit it. Everything between those two poles splits at 50 percent.
Informational modifiers that don’t replace a payment modifier
QS flags monitored anesthesia care. It tells the payer the service was MAC rather than moderate sedation, and it still needs a payment modifier riding alongside it. The AMA maintains the underlying code set; the American Medical Association publishes the annual descriptors that these anesthesia billing modifiers attach to.
G8 and G9 apply when their clinical criteria are met and documented. GC covers resident involvement under teaching physician direction. None of the three prices a claim on its own.
Appending G8 or G9 without documentation that supports them creates real exposure. Reviewers pull these specifically, because they signal a level of complexity that’s easy to assert and hard to prove after the fact.
How modifier pairs break across two claims
On a medically directed case, two providers submit two separate claims for one patient. The anesthesiologist reports QK or QY. The CRNA reports QX. That answers what modifier is used for medically directed CRNA services, and it’s where the trouble starts.
If the modifiers don’t agree across both claims, most payers deny one or both without human review. The qx modifier on the CRNA claim has to match the QK on the physician claim, case by case.
The failure is almost never a coding decision. Two different people build the two claims, sometimes on different days, and nobody reconciles them before submission. It’s a sequencing problem wearing a coding problem’s clothes.
What are the seven elements of medical direction?
Medical direction pays at the medically directed rate when an anesthesiologist directs 2 to 4 concurrent cases and personally performs all seven activities CMS requires. Miss one and the case isn’t medically directed, regardless of what the schedule shows. Above 4 concurrent cases, the service becomes medical supervision and reports with AD.
The seven elements CMS requires
CMS anesthesia billing guidelines list these in the Medicare Claims Processing Manual. All seven apply on every medically directed case, whatever anesthesia CPT codes the case carries.
- Perform a pre-anesthetic examination and evaluation.
- Prescribe the anesthesia plan.
- Personally participate in the most demanding portions of the plan, including induction and emergence where applicable.
- Ensure that any procedures not personally performed are performed by a qualified individual.
- Monitor the course of anesthesia administration at frequent intervals.
- Remain physically present and available for immediate diagnosis and treatment of emergencies.
- Provide indicated post-anesthesia care.
Concurrency counts by overlap and total case load, not by payer. CMS anesthesia concurrency modifiers apply based on how many cases run at once, whether or not the other patients are Medicare beneficiaries. Groups that count only their Medicare cases end up billing QK on days that were structurally AD.
Medical direction versus medical supervision
The distinction decides both the modifier and the rate. Medical direction is QK at 2 to 4 concurrent cases with all seven elements performed. Medical supervision is AD above 4 concurrent cases, and it pays differently.
Reporting QK without documentation supporting all seven elements is one of the most common recoupment triggers in anesthesia audits. Auditors rebuild the timeline from your records. If the records can’t rebuild it, the claim is exposed regardless of what happened clinically.
Can a CRNA and an anesthesiologist both bill?
Yes. On a medically directed case, both providers submit claims for the same patient, and each is paid on 50 percent of the sum of base and time units multiplied by the applicable locality conversion factor.
| Care model | Physician reports | CRNA reports | Payment split |
|---|---|---|---|
| CRNA practicing independently, no physician direction | No claim | QZ | CRNA at full allowable |
| Medical direction, 2 to 4 concurrent cases | QK | QX | 50 percent each |
| Medical direction, one CRNA | QY | QX | 50 percent each |
| Medical supervision, more than 4 concurrent cases | AD | Per state scope rules | Reduced supervision rate |
| Anesthesiologist personally performed | AA | No claim | Physician at full allowable |
Table 9. Anesthesia care team billing scenarios. Payment splits reflect Medicare policy. Source: Medicare Claims Processing Manual, Pub. 100-04, Chapter 12.
The two claims have to agree. Your physician’s QK and your CRNA’s QX describe the same case from two sides, and a payer that receives one without the other denies the one it got.
If your physician and CRNA claims get built by different people on different days, the modifier pair will break sooner or later. A reconciliation check before submission catches it while the claim can still be fixed.
Does Medicare pay qualifying circumstances codes?
No. Qualifying circumstance codes 99100, 99116, 99135, and 99140 carry status indicator B on the Medicare Physician Fee Schedule, which means bundled. They deny to provider liability on Medicare fee-for-service claims and under Medicare Advantage. Many commercial contracts do recognize them and add units.
Why 99100 to 99140 deny on Medicare claims
A status indicator governs payability. It says nothing about whether the code is valid or whether the clinical circumstance happened. The 99100 CPT code is real, the 82-year-old on the table was real, and Medicare has decided the payment sits inside the anesthesia service already.
We cover the same mechanism on a telehealth code in our guide to status indicator denials, where CMS assigns a published rate to a code it won’t pay. Check any code yourself through the CMS fee schedule lookup before you argue with a payer about it.
Keep reporting them when the record supports it. The documentation habit carries across payers, and a claim built to a lower standard for Medicare gets built to that same lower standard when the commercial claim goes out next week.
What commercial payers do instead
Many commercial contracts recognize qualifying circumstances and add units for them. Recognition isn’t universal, and it’s contract-specific rather than carrier-specific. Two plans from the same national payer can answer this differently.
Run the check yourself. Pull 90 days of remittances, filter for claims carrying a qualifying circumstance code, and compare the allowed amount against the same procedure without one. Identical allowed amounts mean that payer isn’t recognizing the code.
That answer belongs in the contract file, not in a coder’s memory. The same recognition question applies to P3 through P5 modifying units, which some contracts pay and others ignore without telling anyone.
Is CPT 99152 an anesthesia code?
No. CPT 99152 is a moderate sedation code, not an anesthesia code. Moderate sedation runs 99151 to 99157 and sits in the Medicine section of CPT, reported by the physician performing the procedure. Anesthesia codes run 00100 to 01999 and get reported by an anesthesia provider on the unit-based formula.
Moderate sedation codes 99151 to 99157
Age splits the two base codes. CPT 99151 covers patients younger than 5 years. CPT 99152 covers patients 5 years and older. Both report the first 15 minutes of intraservice time.
Three rules govern the whole family, and the 99152 CMS guidelines turn on all three.
- The same provider performs both the procedure and the sedation.
- An independent trained observer monitors the patient throughout.
- At least 10 minutes of intraservice time is required to report the initial code.
That 10-minute floor decides more emergency department claims than anything else on the list. A sedation that ran 8 minutes doesn’t reach the initial moderate sedation cpt code, and billing it anyway is the kind of error that repeats across an entire ED case list before anyone notices.
The AAOMS anesthesia coding paper carries the full descriptor set for the range, including the deep sedation cpt code boundaries that separate moderate sedation from anesthesia services.
Which codes are base codes and which are add-on codes
Published guidance gets this wrong often enough to matter. CPT 99153 and 99157 are add-on codes, reporting each additional 15 minutes of intraservice time. CPT 99152 and 99156 are base codes, reporting the first 15 minutes.
Treat a base code as an add-on and your claim goes out without a primary. Treat an add-on as a base code and it goes out without the service it’s supposed to attach to.
When an anesthesia provider is in the room instead
A separate anesthesia provider changes the code set. That claim goes out on the 00100 to 01999 range with a payment modifier, plus QS when the service is monitored anesthesia care.
The misbilling scenario runs the other direction. A proceduralist sedates the patient, and the claim goes out under an anesthesia CPT code anyway. You get either an overbill or a coordination conflict when a separate anesthesia provider bills the same case, and the second claim is the one that denies.
The cpt code for iv sedation follows the same logic. The route doesn’t pick the code family. The provider and the depth of service do.
What is not an anesthesia CPT code?
Three services get billed with anesthesia codes by mistake. Interventional pain procedures use standard surgical CPT codes. Local anesthesia administered by the operating surgeon generates no separate anesthesia code. Dental sedation billed to a dental plan uses CDT codes, not CPT. None of the three pays on the anesthesia unit formula.
Interventional pain procedures
Anesthesia CPT codes for pain management is a search that contains its own error. Epidural steroid injections use the 62321 to 62327 range. Nerve blocks use 64400 to 64450. Both are standard surgical CPT codes billed at the full procedure fee.
No base units. No time units. No conversion factor. The cpt code for lumbar esi prices like any other procedure code on your fee schedule.
One distinction trips up new coders. An anesthesia provider performing a pain procedure bills the procedure code. An anesthesia provider furnishing anesthesia for someone else’s pain procedure bills from the anesthesia range. Same provider, different service, different code family.
Local anesthesia by the operating surgeon
When the surgeon administers local infiltration, there’s no separate anesthesia code and no separate claim. The service is part of the surgical procedure, and a cpt code local anesthesia line on the claim gets bundled out.
CMS states the rule directly. With limited exceptions, Medicare doesn’t allow separate payment for anesthesia performed by the same physician who furnishes the medical or surgical service. Payment sits inside the procedure payment, and under OPPS it’s packaged.
Dental anesthesia and CDT codes
The code set follows the plan, not the chair. Dental anesthesia billed to a dental plan uses CDT codes maintained by the American Dental Association. The same service billed to a medical plan under a medical necessity policy uses a general anesthesia cpt code from the 00100 to 01999 range.
Practices that bill both sides run two code sets for one clinical service. Mixing them produces a denial that reads as a coding error and is a routing error.
Practices billing both a dental and a medical plan for the same sedation service usually find the code-set mismatch through denials rather than a policy review. A code-set audit finds it faster.
Which anesthesia codes were retired but still get billed?
Three retired code sets still show up in published anesthesia coding guides. CPT 00810 and 00740 were deleted effective January 1, 2018. Moderate sedation codes 99143 to 99145 and 99148 to 99150 were deleted effective January 1, 2017. A claim carrying any of them denies before it reaches an adjudicator.
Anesthesia codes deleted in 2018
CPT 00810 covered lower GI endoscopy. It was replaced by three codes: 00811 for lower GI endoscopy not otherwise specified, 00812 for screening colonoscopy, and 00813 for combined upper and lower endoscopy.
CPT 00740 covered upper GI endoscopy. It was replaced by 00731 for upper GI endoscopy not otherwise specified and 00732 for ERCP.
Code 00810 still appears in cheat sheets, base unit tables, and calculator tools as the current anesthesia for colonoscopy cpt code. It isn’t one. A charge master carrying 00810 produces a denial on every colonoscopy case until somebody pulls it out, and most teams find it through a remittance rather than a review.
Moderate sedation codes deleted in 2017
CPT 99143 to 99145 and 99148 to 99150 were replaced by 99151 to 99157 effective January 1, 2017. That was nine years ago, and both ranges still turn up in live billing guidance and in anesthesia CPT codes 2024 reference sheets that never got refreshed.
Search your own charge master for all six of those codes before your next quarter closes. It takes four minutes.
How to check the current code set
Check any anesthesia CPT code against the current AMA CPT code set and the AMA’s posted errata and technical corrections. For Medicare bundling and correct-coding rules, check the CMS NCCI Policy Manual chapter covering anesthesia services.
For 2026, the AMA released 288 new codes with 84 deletions and 46 revisions, 418 changes in total, all effective January 1, 2026. Review the anesthesia section against the published code set rather than against last year’s cheat sheet.
Which NCCI rules cause anesthesia denials?
CMS NCCI Chapter 2 sets the national correct-coding rules for anesthesia CPT codes. Three of them drive most anesthesia bundling denials: when a post-operative pain block is separately reportable, when anesthesia by the operating physician isn’t separately payable, and how CPT 01996 gets reported after the day of surgery.
Post-operative pain blocks
Coding general anesthesia with a nerve block is conditional, and the CMS NCCI policy manual spells out both sides. Epidural and peripheral nerve block injections for post-operative pain management may be separately reportable under some conditions and aren’t under others, depending on the mode of anesthesia and whether the intraoperative anesthetic depended on the block.
The mechanical rule is worth memorizing. When a post-operative pain block is separately reported on the same date as an anesthesia code, modifier 59 or XU may be appended to indicate post-operative pain management.
Documentation carries the weight. The record has to show the block was placed for post-operative pain rather than as the anesthetic itself. That distinction is what the payer is checking, and a block note that doesn’t state the purpose leaves the claim undefended.
Anesthesia by the operating physician
Under CMS anesthesia rules, with limited exceptions, Medicare doesn’t allow separate payment for anesthesia furnished by the physician who also performs the medical or surgical service. Payment sits inside the procedure payment, and under OPPS it’s packaged.
Billers ask about the anesthesia by the surgeon modifier constantly, usually after a surgeon documents administering sedation and somebody tries to bill for it. There isn’t a modifier that unlocks that payment on a Medicare claim.
CPT 01996 and daily epidural management
CPT 01996 covers daily hospital management of continuous epidural or subarachnoid drug administration. Three rules govern it, and few published guides carry all three together.
- CMS doesn’t recognize time units for 01996. It’s a flat service, not a time-based one.
- 01996 is separately payable after the day of surgery, not on the surgery date.
- Payment is limited to one unit per post-operative day.
That third rule cuts both ways. Practices bill multiple units per day and create an overpayment, or they skip the code entirely across a five-day epidural and leave four days of legitimate revenue uncollected.
Why do anesthesia claims get denied?
Anesthesia denials cluster into eight patterns, and most start upstream of the coder. Code mismatch against the surgical claim, modifier pair breaks between the physician and CRNA claims, time documentation gaps, unsupported physical status, and unsupported qualifying circumstances account for the majority. Read the CARC and the RARC together before deciding whether the claim needs a correction or an appeal.
The eight anesthesia denial patterns
| Denial pattern | What happened | The fix |
|---|---|---|
| Code mismatch with the surgical claim | Anesthesia CPT doesn’t align with the surgeon’s CPT | Recode from the ASA Crosswalk using the operative report |
| QK or QY and QX pair mismatch | Physician and CRNA claims carry inconsistent modifiers | Reconcile both claims before submission, not after denial |
| Missing or inconsistent anesthesia times | Start or stop time absent, or conflicts with the op note | Correct from the anesthesia record and resubmit |
| Physical status unsupported | P3 or above assigned without pre-op documentation | Downcode to the supported status or supply the evaluation |
| Qualifying circumstance unsupported | +99140 billed without an emergent indication documented | Remove the add-on or document the indication |
| Qualifying circumstance billed to Medicare | Status indicator B code submitted to Medicare | Expected denial, adjust the payer routing rule |
| Retired code on the claim | 00810, 00740, or 99143 to 99150 still in the charge master | Replace with the current code and purge the master |
| Post-op pain block without modifier | Block reported same-date without modifier 59 or XU | Append the correct modifier and resubmit as a corrected claim |
Table 10. Common anesthesia denial patterns and corrections. Source: CMS NCCI Policy Manual, Medicare Claims Processing Manual Chapter 12.
Six of those eight start before anyone opens the coding queue. Your coder is the last person to touch the claim, not the first, which is why anesthesiology cpt codes accuracy alone won’t move a denial rate. denial management services work the pattern behind the claim.
What to check before you appeal
Read the CARC and the RARC together. One without the other routes the claim into the wrong work queue, and ANSI codes in medical billing are specific enough to tell you which queue that is.
Decide correction or appeal before you touch anything. A wrong code, a wrong modifier, and a missing time entry all route to a corrected claim. Filing an appeal on those burns the window while the clock runs.
Check the timely filing deadline first. Anesthesia billing codes that sat in a queue for 90 days sometimes can’t be fixed at all, and knowing that up front saves the effort for claims you can still recover.
When a QK and QX pair keeps breaking under one payer, QK QX denial recovery starts with the submission sequence rather than the appeal letter.
Fixing the pattern instead of the claim
When the same denial repeats under one payer, the routing rule or the documentation template is the problem. Working that denial recovers one claim. Fixing the upstream rule recovers every future one, which is the whole argument for treating anesthesia billing and coding as a workflow question.
The HHS-OIG numbers make the scale concrete. That 2025 audit found 20 of 28 sampled anesthesia sessions lacking documentation adequate to support the billed service. Twenty out of twenty-eight is a template finding, not twenty separate coder mistakes, and revenue cycle management is where a template gets rebuilt.
If the same anesthesia denial keeps landing under one payer, the fix sits upstream of the claim. ClaimMax RCM sorts each denial into correction, records, or appeal, then traces the pattern back to the rule that produced it. Ask us to look at a 90-day sample.
Anesthesia CPT code FAQ
What is the range of CPT codes for anesthesia?
Anesthesia services run 00100 to 01999. Qualifying circumstances run 99100 to 99140 as add-on codes. Moderate sedation runs 99151 to 99157 in the Medicine section. All three appear on anesthesia claims, and only the first is a cpt code for general anesthesia range.
What is the standard formula for anesthesia CPT coding?
Base units plus time units plus modifying units, multiplied by the conversion factor, or (B + T + M) x CF. Base units are fixed by code. Time units are minutes divided by 15, to one decimal. Modifying units come from physical status and qualifying circumstances.
Does Medicare pay for CPT code 99100?
No. CPT 99100 carries status indicator B on the Medicare Physician Fee Schedule, meaning bundled, and it denies to provider liability on fee-for-service and Medicare Advantage claims. Many commercial contracts recognize it and add 1 unit.
Can a CRNA and anesthesiologist both bill?
Yes, on a medically directed case. The anesthesiologist reports QK or QY and the CRNA reports QX, with each paid on 50 percent of base plus time units. Anaesthesia modifiers have to match across both claims or the payer denies one of them.
What are the CMS anesthesia billing guidelines?
Two documents govern Medicare anesthesia billing. The Medicare Claims Processing Manual, Pub. 100-04, Chapter 12 covers time, modifiers, and medical direction. The CMS NCCI Policy Manual Chapter 2 covers bundling, post-operative pain blocks, and correct coding.
How do I bill for anesthesia?
Submit three things: the anesthesia CPT code describing the service, the actual anesthesia time in minutes, and exactly one payment modifier. Informational modifiers like QS ride alongside the payment modifier. A cpt code for anesthesia without a payment modifier won’t price.
What is CPT code 00812 for anesthesia?
CPT 00812 reports anesthesia for a screening colonoscopy. Use 00811 when the lower GI endoscopy is diagnostic or therapeutic rather than screening, and 00813 when upper and lower endoscopy happen in the same session. All three replaced the deleted code 00810 in 2018.
Is CPT 99152 an anesthesia code?
No. CPT 99152 is a moderate sedation code from the Medicine section, reported by the physician performing the procedure for patients 5 years and older. Anesthesia codes run 00100 to 01999 and get reported by an anesthesia provider.
Can CPT 99152 and 99153 be billed together?
Yes. CPT 99152 is the base code covering the first 15 minutes of intraservice time. Add-on code +99153 reports each additional 15 minutes. At least 10 minutes of intraservice time is required before you can report the base code at all.
Does CPT 99152 require a modifier?
No provider role modifier is required. CPT 99152 doesn’t take AA, QK, QX, QY, or QZ, because those identify anesthesia providers on anesthesia claims. Payer-specific modifier requirements can still apply, so check the contract before building a scrubber rule.
How many CPT codes are deleted in 2026?
The AMA released 84 deletions for CPT 2026, alongside 288 new codes and 46 revisions, for 418 total changes effective January 1, 2026. Review the anesthesia section against the published code set and the AMA’s posted errata.
What are the CPT guidelines for anesthesia in 2026?
Base units are unchanged across 00100 to 01999. The medicare anesthesia conversion factor 2026 is $20.4976 for non-qualifying APM clinicians and $20.5998 for qualifying APM participants, both effective January 1, 2026 under CMS-1832-F, both before locality adjustment.
More ClaimMax coding guides
Our ClaimMax coding guides cover CPT selection, modifier discipline, and denial root-causes across specialties.
