CPT code 83883: Nephelometric assay, other analytes, light-scatter method2026 Medicare lab fee · Clinical Laboratory Fee Schedule
A nephelometric laboratory assay reported for each analyte when no more specific analyte assay code describes the test.
Medicare pays $13.60 for 83883 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
$13.60
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 8 sections
What 83883 covers
Nephelometry evaluates light scattered by particles in a sample to measure an analyte. Code 83883 identifies this method for an analyte when no more specific applicable assay code describes the test. Report each analyte separately.
Report one unit for each analyte assayed. Laboratory documentation should identify the analyte and support use of nephelometry. Medicare pays code 83883 under the CLFS at one national amount: in 2026, $13.60, unchanged since 2020. That amount applies across localities, with no office or facility payment difference. The test is paid only through the CLFS, with no separate physician fee schedule payment.
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 83883
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 83883. 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 83883 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83883 on the lab fee schedule since 2020
83883 · CLFS 2026 Q4 (current)
$13.60
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.
83883 compared with similar tests
- 83520Quantitative immunoassayNot otherwise specified$17.27
- 83520 describes a quantitative immunoassay not otherwise specified. Choose 83883 when nephelometry is the method and no more specific analyte code applies.
- 82784ImmunoglobulinsIgA, IgD, IgG, or IgM$9.30
- 82784 is for quantitative immunoglobulin testing. Use 83883 only when no more specific code covers the analyte and the assay is nephelometric.
- 83873CSF myelin proteinMyelin basic protein$17.20
- 83873 identifies a cerebrospinal fluid protein assay. Use 83883 for another analyte measured by nephelometry when no more specific code describes the test.
83883 billing questions
When should this code be selected instead of an analyte-specific code?
Use it for a nephelometric assay when no more specific applicable code describes the analyte and test. When a specific analyte code applies, report that code instead.
How many units should the laboratory report?
Report one unit for each analyte assayed. Documentation should identify the analyte and support use of nephelometry.
How does this code differ from 83520?
Code 83883 identifies nephelometry as the method. Code 83520 describes a quantitative immunoassay not otherwise specified; select the code that matches the test performed.
Is there a separate Medicare payment for physician interpretation?
No separate physician fee schedule payment is assigned to this test. Medicare pays it through the CLFS.
Does the CLFS amount vary by location or setting?
No. Medicare pays one national amount for the code across localities, with no office or facility payment 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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