Every surgery center and hospital outpatient department has cases that stop before they finish: a blood pressure spike in pre-op, a reaction to sedation, an unexpected finding on the table. The facility has already spent staff time, supplies and OR minutes, and the choice of modifier 73 vs 74 decides whether it recovers half the payment, all of it or nothing.
The rule is simple once you know where the line falls: use 73 when a case stops after prep but before anesthesia, and 74 when it stops after anesthesia starts or the procedure begins. This guide explains how each modifier pays, which cancellations qualify, what to report when several procedures were planned, and how facility modifiers differ from the physician modifier 53.
Modifier 73 vs 74: The Anesthesia Line
The only question that separates the two modifiers is whether anesthesia started or the procedure began before the case stopped.
Modifier 73: stopped before anesthesia
Use 73 when the patient reached the procedure room after prep, but the case stopped before anesthesia started or the procedure began. In that case, Medicare pays the ASC 50% of the rate.
Modifier 74: stopped after anesthesia or incision
Use 74 when anesthesia had started or the procedure had begun, even if only briefly. Medicare pays the full rate, because the facility used nearly the same resources as a completed case.
What counts as anesthesia
Specifically, local anesthesia, a regional block, moderate or deep sedation, and general anesthesia all count. Once the patient receives any of them, the case moves from 73 to 74.
Under the CMS Claims Processing Manual (Chapter 14, section 40.4), a case that stops before the patient reaches the procedure room is not billable at all. Once the patient is in the room and prepped, the anesthesia start decides the modifier.
Which Cancellations Qualify for Modifier 73 vs 74
Modifiers 73 and 74 are for cases stopped because of extenuating circumstances or a threat to the patient’s well-being, not for scheduling decisions.
Cases to bill with 73 or 74
- New arrhythmia, hypotension or hypertension after the patient is prepped
- Allergic or adverse reaction to sedation or a block
- Equipment failure discovered once the patient is in the room
- An intraoperative finding that makes continuing unsafe
Cases not to bill
- Elective cancellations by the patient or surgeon
- Cases cancelled at intake, such as a patient reporting a cold or flu, before reaching the room
- Rescheduling for missing labs, consent or authorization
How Payers Pay Modifier 73 vs 74
Medicare ASC payment follows a simple rule, but a few details change the final amount:
- Modifier 73: 50% of the ASC rate, with no further multiple procedure discount.
- Modifier 74: the full rate, and the line may still take the multiple procedure discount.
- Device-intensive procedures with 73: since 2016, CMS removes the device portion first, then applies the 50% reduction, because the surgeon never implanted the device.
Commercial payers usually follow the same 50% and 100% pattern; Priority Health, for example, pays 73 at 50% and 74 without reduction. Contracts can differ, so confirm terms, especially for implant-heavy cases covered by carve-outs. Our guide to ASC implant carve-out billing covers how those device terms are paid.
When Several Procedures Were Planned
Many ASC cases book two or three procedures. CMS outpatient guidance sets a clear order:
- Some procedures finished: bill the completed procedures normally, and do not report the planned ones that never started.
- None finished: report only the first planned procedure, with 73 or 74 based on anesthesia timing.
- A procedure started but did not finish: report it with 74, along with any procedures already completed.
As a result, the claim never lists services that did not happen. For more on ASC claim structure, see our ASC billing and coding strategies.
Facility vs Physician Modifiers: 73, 74, 52 and 53
Facilities and physicians use different modifiers for the same stopped case, a common source of mismatched claims. For a refresher on how modifiers work, see our guide to modifier codes in medical billing.
| Modifier | Reported by | Use when |
|---|---|---|
| 73 | Facility | Stopped after prep, before anesthesia |
| 74 | Facility | Stopped after anesthesia or start |
| 52 | Facility or physician | Reduced service; facility case with no anesthesia needed |
| 53 | Physician | Procedure stopped after it began |
In other words, the surgeon never uses 73 or 74, and the facility never uses 53. When a case stops before anesthesia, the surgeon generally has no procedure to bill. Our overview of anesthesia modifiers covers how the anesthesia provider reports the same case.
Documentation That Supports the Claim
Because payers may request records to confirm when and why the case stopped, the operative and nursing notes should show:
- Time the patient entered the room
- Anesthesia start time, or a note of no anesthesia
- Clinical reason the case stopped
- What was completed, including any incision, scope insertion or device opened
- The surgeon decision and patient condition at discharge
If the anesthesia start time is missing, the payer may downgrade a 74 claim to 73.
How to Bill a Discontinued Case, Step by Step
- Confirm the case qualifies: the patient was in the room after prep, and the stop was for safety or an extenuating circumstance.
- Find the anesthesia start time in the anesthesia or nursing record.
- Choose the modifier: 73 if the case stopped before that time, 74 if after.
- Select the procedure: completed procedures bill normally; if the surgeon finished none, report only the first planned procedure.
- Check device and discount rules: device-intensive lines with 73 lose the device portion; 74 lines may take the multiple procedure discount.
- Align with the surgeon claim, which uses 53 if the procedure had started and nothing if it had not.
- Attach or retain notes showing the times and the reason the case stopped.
Five Discontinued-Case Scenarios
| Scenario | Facility claim | Surgeon claim |
|---|---|---|
| Cataract: hypertension in the room, before the block | 66984-73 | None |
| Colonoscopy: obstruction after sedation | 45378-74 | 45378-53 |
| Carpal tunnel done; trigger finger stopped after anesthesia | 64721; 26055-74 | 64721; 26055-53 |
| Fever reported at intake | None | None |
| Implant case stopped before anesthesia, device unopened | Procedure-73, device portion removed | None |
In each case, the timing in the record, not the surgeon intent, decides the modifier.
Recover Payment on Every Stopped Case
Modifier 73 vs 74 comes down to one documented moment: whether anesthesia started or the procedure began before the case stopped. Get that time into the record, report only what was planned and started, keep facility and physician modifiers separate, and discontinued cases recover the payment they are owed instead of turning into denials or write-offs.
If cancelled cases are slipping through as unbilled or underpaid, MBW RCM can help. Through our ASC billing services, we review discontinued cases, apply the right facility modifiers and follow each claim through payment.
Modifier 73 vs 74 FAQs
What is the difference between modifier 73 and 74?
Modifier 73 is for a facility procedure stopped after prep but before anesthesia; modifier 74 is for one stopped after anesthesia started or the procedure began.
How much does Medicare pay for modifier 73 and 74 in an ASC?
Modifier 73 pays 50% of the ASC rate, and modifier 74 pays the full rate, which may still be subject to the multiple procedure discount.
Can a physician use modifier 73 or 74?
No, because they are facility modifiers. A physician reports a procedure stopped after it began with modifier 53.
Should an elective cancellation be billed with modifier 73?
No. Modifiers 73 and 74 apply only to cases stopped for extenuating circumstances or patient safety, not elective cancellations.
Do hospital outpatient departments use modifiers 73 and 74?
Yes. Hospital outpatient claims use the same two modifiers and the same anesthesia timing rule, with 73 paid at a reduced rate and 74 paid in full.
Which procedure is reported when several were planned?
Bill completed procedures normally. If the surgeon finished none, report only the first planned procedure with 73 or 74.