CPT code 61799: Cranial radiosurgery, each additional complex lesion2026 Medicare rate & RVUs in Michigan
Reports each additional complex intracranial lesion treated during a cranial stereotactic radiosurgery session when the primary complex-lesion service is also reported.
CMS doesn’t publish an office rate for 61799 in Michigan.
Medicare allowed amount for participating (non-QP) physicians, before deductible, coinsurance and claim adjustments. Not a patient’s bill or a hospital charge.
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What 61799 covers
This add-on represents treatment of another complex intracranial lesion during cranial stereotactic radiosurgery. SRS delivers focused radiation to a defined target using stereotactic localization. Neurosurgeons and radiation oncologists may participate in planning and treatment, commonly for intracranial tumors or vascular lesions. The complex-versus-simple classification follows the applicable CPT criteria; the lesion diagnosis alone does not establish the code level.
Report 61799 for each additional complex lesion treated in the same service, with 61798 for the primary complex lesion. The record should support the number of distinct lesions treated and the basis for classifying them as complex under CPT guidance. CMS identifies 61799 as an add-on code: it is billed only with a primary procedure and paid within that procedure’s global period.
This summary was written with AI assistance from CMS physician fee schedule data and checked against the CMS billing rules shown here. Rates on this page come directly from CMS files.
Where 61799 pays more and less in Michigan
| Payment locality | Office | Facility |
|---|---|---|
| Detroit, MI | Unavailable | $317.87 |
| Rest of Michigan | Unavailable | $279.14 |
How the 61799 rate is calculated
Each of 61799’s three RVUs is multiplied by a geographic index (GPCI) for the payment locality, added up, and multiplied by the conversion factor. Drag the indexes or enter a ZIP to see what moves the rate.
How the rate is built · 61799
RVUs × geographic indexes × conversion factor
Work4.69
4.69 RVUs× 1.000 GPCI
Practice expense1.63
1.63 RVUs× 1.000 GPCI
Malpractice1.93
1.93 RVUs× 1.000 GPCI
Adjusted RVUs
8.2500
Conversion factor
$33.4009
Medicare rate
$275.56
Every GPCI starts at 1.000, the national rate. Enter a ZIP or drag a slider.
Payment rules and modifiers for 61799
The CMS indicators that decide how 61799 is paid alongside other services.
CMS payment indicators · 61799
Cranial radiosurgery, each additional complex lesion
| Rule | CMS value | What it means |
|---|---|---|
| Global period | ZZZ | Add-on code: falls within the primary procedure’s global period. |
| Multiple procedures | 0 | No multiple-procedure reduction. |
| Bilateral (modifier 50) | 0 | The 150% bilateral adjustment doesn’t apply. |
| Assistant at surgery (80/81/82/AS) | 2 | Paid. |
| Co-surgeons (62) | 0 | Not permitted. |
| Team surgery (66) | 0 | Not permitted. |
| Professional/technical | 0 | Physician service: no professional/technical split. |
What modifiers do to the payment
Modifier 80 · payment effect
With and without the modifier
61799 without 80 · national facility
$275.56
Cranial radiosurgery, each additional complex lesion
61799-80 · Assistant: 16%
$44.09
A physician assistant at surgery is paid 16% of the surgeon’s fee schedule amount.
61799 compared with similar codes
Compare codes · National
4 codes, side by side
How to choose
- 61798Cranial radiosurgeryComplex lesion
- 61798 reports the primary complex cranial lesion; 61799 reports each additional complex lesion in the same SRS service.
- 61797Cranial radiosurgeryEach additional simple lesion
- Both are additional-lesion SRS codes. The distinction is whether the lesion meets the CPT criteria for complex or simple classification.
- 61796Cranial radiosurgerySimple lesion
- 61796 is the primary code for a simple cranial lesion. It is not the add-on for an additional complex lesion.
61799 billing questions
Which primary code must accompany 61799?
For additional complex cranial lesions, report 61799 with 61798 for the primary complex lesion. The add-on code is not reported by itself.
How many units of 61799 should be reported?
Report one unit for each additional complex lesion treated. The record should make the number of separately treated lesions clear.
How is 61799 distinguished from 61797?
Both report additional cranial lesions treated with SRS. Use 61799 for a complex lesion and 61797 for a simple lesion, applying the CPT criteria for that distinction.
Does the diagnosis determine whether a lesion is complex?
No. A diagnosis such as an intracranial tumor or vascular lesion does not by itself establish complexity; the applicable CPT criteria support the code level.
What documentation supports 61799?
Document the SRS treatment, each lesion treated, and the basis for classifying the additional lesion as complex under CPT guidance. The primary complex-lesion service should also be documented and reported.
Where these rates come from
FeeBase calculates base physician payments from CMS work, practice-expense and malpractice RVUs, adjusted by each locality’s geographic indexes and the conversion factor. Services without a published rate are labeled, never given a made-up amount. Amounts are Medicare allowed amounts before claim adjustments: not a patient’s bill or a commercial rate.
CMS RVU26D · effective Oct 1, 2026 through the day before Jan 1, 2027
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