Billing modifier · CMS claims manual

Modifier 73: a facility procedure stopped before anesthesia.

Modifier 73 is used by a hospital outpatient department or ambulatory surgical center to report a procedure requiring anesthesia that was terminated after the patient was prepared and taken to the procedure room but before anesthesia was given. Medicare pays 50 percent of the full payment amount.

Sources: CMS manuals · retrieved November 2, 2026Reference page · nothing is sent or stored

Modifier 73 at a glance

Modifier: 73: Discontinued Outpatient Procedure Before Anesthesia
Used on: Facility (hospital outpatient or ASC) procedure stopped before anesthesia
Medicare rule: Paid at 50% of the full payment amount
Primary source: CMS Ch. 4 s.20.6.4; Ch. 14 s.40.4

What CMS says

CMS chapter 4, section 20.6.4 says modifier 73 is used by the facility when a procedure requiring anesthesia was terminated due to extenuating circumstances or circumstances that threatened the well-being of the patient, after the patient had been prepared (including pre-medication when provided) and taken to the room, but before anesthesia. For billing hospital outpatient services, anesthesia includes local, regional block(s), moderate sedation, deep sedation and general anesthesia. The modifier lets the facility’s preparation and room costs be recognized.

Modifiers 73 and 74 are only used for discontinued procedures for which anesthesia is planned or provided.

How it is paid

Hospital OPPS: 50 percent of the full OPPS payment amount. For device-intensive procedures with modifier 73, CMS reduces the APC payment by 100 percent of the device offset amount before the other adjustments, a rule in force since January 1, 2016.

ASC: 50 percent of the rate for modifier 73, and nothing is paid if the procedure is terminated before the patient is taken into the treatment or operating room (chapter 14, section 40.4). Services billed with 73 or 52 are not subject to the multiple procedure discount.

Worked example with a hypothetical $3,000.00 OPPS payment: a qualifying 73 line is paid at 50 percent, $1,500.00, before copayment and deductible.

73 versus 74

Modifier 74 applies when the procedure was stopped after anesthesia was induced or the procedure started (for example incision made, intubation started or scope inserted); CMS pays the full amount under OPPS. An ASC claim for a terminated surgery must have an operative report on file stating the reason for termination, the services and supplies actually provided and not provided, the time spent in each stage, and the HCPCS code for the procedure had it been performed.

Look-alike modifiers

Modifier 52: Reduced services, no anesthesia planned.
Modifier 53: Discontinued physician service.
Modifier 51: Multiple procedures.

The full modifier descriptions are in the AMA CPT code book and the HCPCS Level II code set; this page covers only what the CMS claims manuals say about modifier 73.

Sources

CMS: Medicare Claims Processing Manual, Chapter 4 (Rev. 13799, issued 05-28-26) — section 20.6.4, modifiers 73 and 74 (retrieved 2026-11-02)
CMS: Medicare Claims Processing Manual, Chapter 14 (Rev. 13836, issued 06-24-26) — sections 40.4 and 40.5, terminated procedures and multiple procedures (ASC) (retrieved 2026-11-02)

Every rule above was read from these CMS pages on November 2, 2026. Payers revise policies and contracts, so confirm anything that affects a claim with the payer or your Medicare Administrative Contractor.

Frequently asked questions

What is the payment for modifier 73?

Fifty percent of the full OPPS payment amount, and 50 percent of the rate in an ASC, per CMS chapters 4 and 14.

What is the difference between modifier 73 and 74?

73 is for a procedure stopped before anesthesia; 74 is for one stopped after anesthesia was given or the procedure started, and is paid in full under OPPS.

Do physicians use modifier 73?

It is a facility modifier for hospital outpatient departments and ASCs. CMS describes modifier 53 for discontinued physician services.

Not legal, billing or medical advice

This page explains published CMS manual text. It cannot see your claim, your contract or any payer’s policy. Confirm with the payer or your Medicare Administrative Contractor (MAC) before you bill, resubmit or appeal.