CPT code 83950: HER-2/neu assay, serum oncoprotein measurement2026 Medicare lab fee · Clinical Laboratory Fee Schedule
This serum laboratory assay measures HER-2/neu oncoprotein and is reported as a circulating tumor-marker test, including in breast cancer monitoring.
Medicare pays $64.41 for 83950 under the 2026 Clinical Laboratory Fee Schedule: one national amount, the same in every state and setting.
Medicare lab fee · CLFS 2026 Q4
National CLFS amount
$64.41
In effect since Jan 1, 2026. The same amount in every state, payment locality and setting.
- Geographic adjustment
- None
- Office vs facility
- Same
- Since 2020
- Unchanged
- CMS updates
- Quarterly
Medicare pays the lesser of the lab’s charge and this amount. Patients usually owe no Part B deductible or coinsurance for covered clinical lab tests.
On this page 7 sections
What 83950 covers
Code 83950 identifies laboratory measurement of HER-2/neu oncoprotein in serum. Oncology clinicians may order the assay as a circulating tumor marker when monitoring breast cancer, particularly advanced disease. The laboratory performs and reports the measurement. This is distinct from pathology testing of tumor tissue for HER2 protein expression or gene amplification.
Medicare pays 83950 under the CLFS at one national amount, consistent across states and localities and without an office or facility difference. The 2026 national CLFS amount is $64.41, unchanged since 2020. The test is paid only through the CLFS and is excluded from the physician fee schedule.
This summary was written with AI assistance from CMS Clinical Laboratory Fee Schedule data. Amounts on this page come directly from CMS files.
How Medicare pays 83950
Clinical lab tests aren’t priced like physician services. They’re paid from their own fee schedule, with its own rules. See the whole lab fee schedule.
One national amount
CMS sets a single Clinical Laboratory Fee Schedule amount for 83950. There’s no geographic (GPCI) adjustment, so it pays the same in every state and payment locality.
No office or facility rate
Lab tests aren’t built from relative value units, so there’s no office and facility split: the place of service doesn’t change the CLFS amount.
Updated every quarter
CMS republishes the CLFS each quarter. New tests, often proprietary laboratory analyses (PLA codes), join during the year; existing amounts are updated each January.
Excluded from the physician fee schedule
The physician fee schedule lists 83950 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83950 on the lab fee schedule since 2020
83950 · CLFS 2026 Q4 (current)
$64.41
Unchanged since Jan 1, 2020
27 quarterly CLFS releases on file, first CLFS 2020 Q1. A code missing from a quarter wasn’t on that release.
83950 compared with similar tests
- 88360Tumor IHC scoringManual quantitative, per antibody$106.97–$163.58
- 88360 reports manual quantitative immunohistochemical analysis of tumor tissue. Code 83950 is the serum HER-2/neu oncoprotein assay.
- 88361Tumor immunohistochemistryComputer-assisted analysis$102.56–$154.28
- 88361 reports automated image analysis of tissue immunohistochemistry. Code 83950 measures HER-2/neu oncoprotein in serum.
- 83951DCP testDes-gamma-carboxy prothrombin$64.41
- 83951 is the oncoprotein assay for DCP, not HER-2/neu. Select the code for the analyte measured.
- 86300Tumor markerCA 15-3 quantitative assay$20.81
- 86300 reports a CA 15-3 assay, a different tumor marker. It does not report HER-2/neu oncoprotein.
83950 billing questions
What specimen does 83950 measure?
It measures HER-2/neu oncoprotein in serum as a circulating tumor-marker assay.
Does 83950 report tumor-tissue HER2 testing?
No. It reports the serum oncoprotein assay; tissue protein-expression or gene-amplification testing is a separate pathology service.
How is 83950 different from 83951?
83950 measures HER-2/neu oncoprotein, while 83951 is the oncoprotein assay for DCP. Select the code for the analyte measured.
How does Medicare pay for 83950?
Medicare pays the test through the CLFS at one national amount across localities, with no office or facility difference.
Where this amount comes from
FeeBase reads lab amounts directly from the CMS Clinical Laboratory Fee Schedule file for the quarter: one row per code, with its payment indicator and national amount. Contractor-priced tests are labeled, never given a made-up amount. Amounts are Medicare payment limits, not a patient’s bill or a commercial rate.
CMS CLFS 2026 Q4 · effective Oct 1, 2026 through the day before Jan 1, 2027
Show the CMS file line behind this amount
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