SBRT Billing Codes in Medical Billing: 77373, 77435 and the Five-Fraction Course

SBRT billing codes are 77373, the technical code for each delivered fraction of stereotactic body radiation therapy, and 77435, the radiation oncologist’s management code for the entire course, which by definition cannot exceed five fractions. Everything else on an SBRT claim is a planning or physics code that conventional courses use too.

SBRT courses are short and costly, and payers review them closely, so it is worth learning these few codes well.

Where you see it

Place	What goes there
CMS-1500 box 24D and 24G, freestanding center	77373 with no modifier, one unit per treatment date; 77435 with no modifier, one unit for the course
CMS-1500, physician treating a hospital patient	77435 only, plus planning codes with modifier 26; the hospital bills 77373
UB-04 or 837I, hospital outpatient	77373, one unit per treatment date; 77371 or 77372 once for cranial SRS
Medicare Physician Fee Schedule (2026)	77373: PC/TC indicator 3 (technical only), 29.30 RVUs; 77435: indicator 2 (professional only), 19.20 RVUs; both status A, global XXX
OPPS Addendum B (CY 2026)	77373: status S, APC 5626; 77371 and 77372: status J1, APC 5627; 77435: status N; G0339 and G0340: status B

The stereotactic family

Code	Covers	Reported
77373	SBRT treatment delivery, per fraction, one or more lesions, image guidance included	once per treatment date; course not to exceed five fractions
77435	SBRT treatment management, entire course	once per course
77371	Cranial SRS delivery, multisource (cobalt-60 based) unit, complete course of one session	once
77372	Cranial SRS delivery, linear accelerator based, complete course of one session	once
77432	Cranial SRS treatment management, complete course	once per course
61796 to 61800	The neurosurgeon’s stereotactic radiosurgery of cranial lesions, simple or complex, first and each additional lesion, plus headframe application (add-on codes)	per lesion; 90-day global on the primary codes
G0339 and G0340	Robotic linear accelerator radiosurgery, first session and sessions two to five	status B under OPPS and contractor priced in the fee schedule for 2026; see below

The first distinction is body versus cranial. A brain lesion treated in one session is SRS: 77371 or 77372 for delivery, 77432 for the radiation oncologist’s management, and 61796 to 61800 for a participating neurosurgeon. A lesion anywhere else, or a cranial lesion treated in more than one session, is SBRT: 77373 per fraction and 77435 once. 77432 and 77435 are mutually exclusive for a course, and neither is billed with 77427.

Planning codes used with SBRT

Planning uses the same codes as a complex conventional course, done in a week or two:

• 77263 complex planning and 77290 complex simulation, with 77293 (respiratory motion management simulation) as an add-on when a 4D CT or gating assessment is performed.
• 77295 or 77301, one plan per course, with 77338 once per IMRT plan; 77300 and 77334 as documented (2026 MUE of 10 per date for each).
• 77370, special physics consultation, once per course on the physician’s request; SBRT is a common reason.
• Image guidance is included in 77373. The 2026 NCCI Policy Manual says 77371 to 77373 include stereotactic guidance for field placement, and CPT’s 2026 parenthetical says not to report 77402, 77407 or 77412 with 77373, nor the TC modifier with 77371 to 77373.

Hospital billing in 2026

Under the CY 2026 OPPS the hospital bills 77373 at status S in APC 5626 (Level 6 Radiation Therapy), national unadjusted 1,826.78 per fraction. Cranial SRS delivery, 77371 or 77372, is status J1 in comprehensive APC 5627 (Level 7), national unadjusted 7,524.82, which packages the other services on that claim. 77435 is status N on the hospital side because it is a physician service; the radiation oncologist bills it on the professional claim at 19.20 RVUs in either setting.

The robotic G-codes G0339 and G0340 carry status indicator B in the 2026 Addendum B (not recognized under OPPS) and status C (contractor priced) in the Physician Fee Schedule. There is no G-code left for hospital SBRT under Medicare: a hospital reports 77373 whatever the delivery platform.

Fraction limits and prior authorization

• Five fractions is a definition, not a payer preference. Both codes describe a course “not to exceed 5 fractions.” A six-fraction prescription is billed as 77407 or 77412 with 77427 (six fractions is one unit), whatever the technique.
• 77373 pays once per treatment date regardless of lesions or sessions that day, in Noridian’s words; its 2026 MUE is 1. 77435 and 77432 pay once per course, never both, never with 77427.
• Traditional Medicare does not require prior authorization for SBRT. CMS’s hospital outpatient prior authorization program lists blepharoplasty, botulinum toxin, panniculectomy, rhinoplasty, vein ablation, spinal neurostimulators, cervical fusion and facet joint interventions; no radiation service. Medicare Advantage and commercial plans mostly do require it, and the approval sets the fraction count; our post on radiation therapy prior authorization in 2026 covers the process.

Worked example: a five-fraction lung course

A freestanding center treats a peripheral lung lesion in five fractions over ten days. Illustrative figures, 2026 national amounts before geographic adjustment (RVUs from the CMS October 2026 RVU file times the 33.4009 conversion factor).

Line	Units	Note
77263, 77290, 77293, 77301, 77338, 77370	1 each	planning and physics, once per course
77300	3	documented calculations
77334	2	immobilization and a custom device
77373	5	one per treatment date, 978.65 each, 4,893.25
77435	1	management of the course, 641.30

The two SBRT codes alone come to 5,534.55 for the course. Had the same lesion been treated in three fractions, 77373 drops to three units (2,935.95) and 77435 stays at one unit, because it is billed once per course.

In a hospital department the hospital bills the five 77373 units at the APC 5626 rate (9,133.90 national unadjusted) and the radiation oncologist bills 77435 and the planning codes with modifier 26.

What to do

• Check the prescription before the first charge. Six or more fractions means the level delivery code and 77427, not 77373 and 77435.
• Hold 77435 until the course is complete, then post it once with no modifier.
• Never add TC to 77373 or 26 to 77435; each code has a single component.
• Denials to recognize: CARC 151 with RARC N362 when 77373 units exceed one per date or five per course, a correction if the fraction log agrees; CARC 197 when the authorization is missing, or RARC N54 when the claim does not match it, a retro-authorization request or an appeal with the prescription; CARC 4 when a component modifier is appended, a correction; CARC 50 when a coverage criterion is not documented (Noridian, for example, lists a Karnofsky score below 40 or ECOG 3 or worse as not medically necessary), an appeal with the clinical record.
• Iridium Suite’s claim scrubber checks every service line as it is entered against CCI edits, payer rules and radiation oncology frequency rules.

Related terms

• CPT 77427
• Continuing physics 77336 and special physics 77370
• Special treatment procedure 77470
• Modifier 26 and TC
• Medically unlikely edits
• Radiation therapy prior authorization in 2026

Further reading: CMS Medicare Claims Processing Manual, Chapter 13, section 70; CMS CY 2026 OPPS final rule CMS-1834-FC and addenda; Noridian JE Part B, Radiation Oncology; CMS prior authorization for certain hospital outpatient department services.