CPT code 83884: Neurofilament light, light chain assay2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures neurofilament light chain, a marker of axonal injury, for laboratory evaluation of neurologic conditions.
Medicare pays $116.23 for 83884 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
$116.23
In effect since Jan 1, 2026. The same amount in every state, payment locality and setting.
- Geographic adjustment
- None
- Office vs facility
- Same
- Since 2026
- 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 83884 covers
The assay measures neurofilament light chain (NfL), a structural protein associated with nerve-cell axons. NfL is used as a biomarker of axonal injury, so clinicians may order the test when evaluating or following neurologic disorders in which nerve-fiber injury is relevant. Neurology and neuroimmunology clinicians may consider an NfL result alongside symptoms, examination findings, and other diagnostic information; the result is not itself a disease-specific diagnosis. A clinical laboratory performs and reports the assay. Code 83884 identifies the NfL measurement, rather than tests for other proteins.
Medicare pays 83884 through the Clinical Laboratory Fee Schedule (CLFS) at one nationally set amount that applies across states and localities, without an office or facility payment difference. The 2026 national CLFS amount is $116.23. Medicare pays this test only through the CLFS.
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 83884
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 83884. 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 83884 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83884 on the lab fee schedule since 2025
83884 · CLFS 2026 Q4 (current)
$116.23
Unchanged since Jan 1, 2026
Every change on file
- Jan 1, 2026 · CLFS 2026 Q1MAC-priced → $116.23
8 quarterly CLFS releases on file, first CLFS 2025 Q1. A code missing from a quarter wasn’t on that release.
83884 compared with similar tests
- 83873CSF myelin proteinMyelin basic protein$17.20
- 83873 is for a cerebrospinal fluid protein assay, not neurofilament light chain. Use 83884 when the measured analyte is NfL.
83884 billing questions
What does 83884 measure?
It measures neurofilament light chain (NfL), a biomarker associated with axonal injury. Clinicians may use the result in evaluating or following neurologic disorders involving nerve-fiber injury.
How is 83884 different from 83873?
83884 is for neurofilament light chain. 83873 is for a cerebrospinal fluid protein assay, not NfL.
How does Medicare pay 83884?
Medicare pays it through the CLFS at one national amount across localities, with no office or facility payment difference.
Is 83884 paid under the physician fee schedule?
No. Medicare pays this test only through the CLFS.
What should the reported test identify?
The laboratory test should be the neurofilament light chain assay, not a different protein assay.
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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