CPT 77427 in Medical Billing: Radiation Treatment Management, Five Fractions at a Time

CPT 77427 is radiation treatment management: the radiation oncologist’s professional work of managing a patient through a course of external beam radiation, reported once for every five fractions delivered. It is a physician-only code with no technical component, so it never carries modifier 26 or TC.

The code is simple to describe and surprisingly easy to over- or under-count, especially at the end of a course. Here is how the arithmetic works.

Where you see it

Place	What goes there
CMS-1500 box 24D and 24G	77427 with no modifier, one unit per five fractions; the date of service is the date you choose to represent that group of five (see reviewer notes on payer preference)
837P electronic claim	Loop 2400, SV1 segment: procedure 77427, unit count 1
Medicare Physician Fee Schedule	PC/TC indicator 2 (professional only), global period XXX, status A
Remittance advice	One line per unit; Medicare’s allowed amount is the full fee schedule amount for a non-facility or facility site, both the same because there is no practice expense difference by site
Record and verify system	The fraction count that every unit depends on is recorded here, not in the billing system

The management family

Code	Covers	Reported
77427	Radiation treatment management, five treatments	once per five fractions during a course
77431	Management of a course consisting of only one or two fractions	once, for the whole course
77432	Stereotactic radiation treatment management of cranial lesions	once, for the complete course
77435	Stereotactic body radiation therapy management	once, for the complete course

All four carry PC/TC indicator 2 in the 2026 fee schedule. They are mutually exclusive for the same course: a patient receiving SBRT is managed under 77435, not 77427, even though the SBRT course has fewer than five fractions.

The 2026 CPT changes that deleted 77014, 77385, 77386 and 77401 and reorganized treatment delivery into 77402, 77407 and 77412 did not touch the management codes. 77427 and its fraction rules are unchanged; what changed is the delivery code billed alongside it.

How the count works

Medicare’s rule, from the Claims Processing Manual, Chapter 13, section 70.1:

• A unit of treatment management equals five fractions or treatment sessions, “regardless of the actual time period in which the services are furnished.” A week with a holiday and only four treatments is not a billable week by itself; you wait for the fifth fraction.
• At the final billing of the course, three or four fractions beyond a multiple of five are paid as one more unit. One or two fractions beyond a multiple of five are not paid separately; Medicare considers them covered by the earlier payments.
• Two fractions on the same day (hyperfractionation) count as two, provided there was a distinct break between sessions and each fraction is of the kind usually given on separate days.
• If the course ends and then resumes, the payer adjusts to the policy above across the whole course, so two late fractions after a 20-fraction course do not create a fifth unit.

The manual’s own examples: 18 fractions equals 4 units, 62 fractions equals 12, 8 fractions equals 2, 6 fractions equals 1.

Worked examples: 20 fractions and 23 fractions

The 2026 national fee schedule value of 77427 is 5.85 RVUs, which at the 33.4009 conversion factor is about 195.40 per unit before geographic adjustment and sequestration. Illustrative figures.

Course A, 20 fractions, Monday through Friday for four weeks. Units fall after fractions 5, 10, 15 and 20: four units.

Unit	Fractions	Allowed	Medicare 80 percent	Patient 20 percent
1 through 4	1 to 20	4 x 195.40 = 781.60	625.28	156.32

Course B, 23 fractions. Four full units cover fractions 1 to 20. Three fractions remain, so a fifth unit is paid.

Unit	Fractions	Allowed
1 through 4	1 to 20	781.60
5	21 to 23 (the three-or-four rule)	195.40
Course total	23 fractions	977.00

Had the course stopped at 22 fractions, the two leftover fractions would earn nothing, and the total stays at 781.60. Had it stopped at 21, the same. A final unit always needs at least three leftover fractions.

A short palliative course of 5 fractions is one unit of 77427. A single 8 Gy fraction for bone pain is 77431, not 77427. A 15-fraction hypofractionated breast course is three units. A five-fraction prostate SBRT course is one unit of 77435 and no 77427 at all.

What the physician must document

The management code pays for the physician’s oversight of the whole course, and Medicare bundles a long list of services into it (Chapter 13, section 70.2): office visits 99211 through 99215 during treatment, checking of treatment charts, verification of dosage, review and revision of the treatment plan, written progress notes, routine management of unrelated problems, and follow-up examination and care for 90 days after the last treatment. None of those is billed separately.

What supports each unit is the on-treatment visit note: the physician’s assessment of the patient’s tolerance and side effects, review of setup or port images, review of the treatment chart and dose delivered to date, and any change to the plan. The manual states the physician need not personally examine the patient during each fraction; the expectation in practice is one documented physician encounter per billed unit, and most audits of 77427 come down to whether that note exists for each unit.

What to do

• Count fractions, not weeks. Post 77427 from the delivered fraction count in the treatment system, never from the calendar. A missed day moves the unit, it does not remove it.
• Hold the last unit until the course closes. Decide the final unit only when you know the total; three or four leftover fractions bill, one or two do not.
• Do not bill visits during treatment. An E/M during the course is bundled and will deny CARC 97. The exception is a visit for a problem truly unrelated to the cancer and its treatment, and even then Medicare’s bundled list includes “routine medical management of unrelated problem,” so expect to defend it.
• Denials to recognize: CARC 151 (frequency not supported) with RARC N362 (units exceed the acceptable maximum) when units exceed fractions divided by five, or when a unit posts before the fifth fraction; CARC 18 (exact duplicate) when two units carry the same date; CARC 4 with N519 if anyone appends 26. The first two are corrections once the fraction log agrees; the third is a correction and resubmission.
• Iridium Suite counts 77427 units against the delivered fractions imported from the Record & Verify system and flags a unit entered before its fifth fraction.

Related terms

• Modifier 26 and TC
• Global, professional and technical charges
• Claim adjustment group and reason codes
• Remark codes
• RO Model billing

Further reading: CMS Medicare Claims Processing Manual, Chapter 13, section 70 (Radiation Oncology); CMS PFS Relative Value Files; X12 Claim Adjustment Reason Codes.