Who Decides How Often You Can Bill 77436?

Aetna's August provider bulletin spends most of its length on drug lists and precertification before it reaches the sentence that reprices a treatment course.

"Effective November 1, 2026, we'll limit the use of CPT® code 77436 (SGRT) to one reimbursement for the entire course of treatment, regardless of the number of individual treatment sessions."

That applies to commercial and Medicare Advantage members, and Aetna spells out the consequence: claims with multiple units of 77436 in the same course "may be subject to denial or adjustment."

Here is why that one sentence matters more than its placement suggests.

77436 is eight months old, and nobody has settled how often you may report it. The two loudest answers in the market are twenty units a course apart.

A Code That Arrived Without a Frequency

CPT 2026 tore up superficial radiation therapy and rebuilt it as a four-code family.

77401 delivery is gone from the fee schedule entirely, and so is the G6001 ultrasonic guidance code. The clinical treatment planning and simulation codes that dermatology practices leaned on, 77261 through 77263 and 77280, no longer describe this work.

In their place: 77436 for planning and simulation-aided field setting, 77437 for superficial delivery at or below 150 kV, 77438 for orthovoltage delivery above that, and 77439 as the ultrasound image-guidance add-on.

Read 77436's descriptor and you will notice what is missing. It says what the service is, and says nothing about how many times you may report it.

That silence is the whole fight.

One housekeeping note before the money, because it will cost somebody a missed deadline. Aetna labels the item "Surface Guided Radiation Therapy (SGRT)," which is the name of a different technology, the optical surface-tracking used to position patients on a linac. The code cited is 77436 and the documentation Aetna asks for is "treatment planning and simulation" work. If a radiation oncology department files this bulletin under linac positioning, the dermatology line is the one that gets hit.

Three Answers, One Question

"How many units of 77436 does a twenty-fraction course support?"

Answer one, from the vendor. Sensus Healthcare builds the SRT-100 devices most of this volume runs on, and its MedIQ billing service publishes a 2026 coding Q&A. Asked "How often can we do 77436? Does that vary per insurance?", the answer is four words: "Every time and it does not vary per insurance carrier at this time." Elsewhere on the same page: "Currently the 77436 – per lesion/per fraction." Asked whether ultrasound has to be performed to bill 77436 each day, the answer is no, and the page lists three justifications for the daily charge: remarking the lesion site, patient positioning, and prescription changes.

Answer two, from Medicare. The NCCI practitioner MUE table effective July 1 sets 77436 at 1, with adjudication indicator 3 and a rationale field that reads, verbatim, "Code Descriptor / CPT Instruction."

Read that carefully, because it does less than it looks like it does. An MUE is a ceiling on units per date of service. One unit a day for twenty days clears it. Medicare's automated edit does not touch the practice billing 77436 on every fraction; it only stops the practice billing two on one day, and because MAI 3 sums units across all claim lines for the same code and date, modifiers 59 and 76 do not get you around it either. The vendor page recommends exactly those modifiers for a second lesion.

Answer three, from Aetna, starting November 1. One per course.