CPT code 83527: Insulin assay, free fraction2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures free insulin, the fraction not bound to antibodies, and may be reported when antibody-bound insulin could affect interpretation of insulin results.
Medicare pays $12.95 for 83527 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
$12.95
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 83527 covers
CPT 83527 reports measurement of free insulin—the fraction not bound to circulating antibodies. A clinician may order it when antibody-bound insulin could complicate interpretation of insulin results, including during evaluation of unexplained hypoglycemia. A clinical laboratory performs the assay and reports the result to the ordering clinician, such as an endocrinologist.
Report this code for the free insulin measurement, not for a total insulin result. Free and total insulin are distinct assays; both may be reported when each is performed and documented. Medicare pays the test through the CLFS, with one national amount across states and localities and no geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $12.95, unchanged since 2020. The test is paid only under the CLFS, not 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 83527
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 83527. 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 83527 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83527 on the lab fee schedule since 2020
83527 · CLFS 2026 Q4 (current)
$12.95
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.
83527 compared with similar tests
- 83525Insulin assayTotal insulin$11.43
- Choose 83527 for free insulin and 83525 for total insulin. The two results represent different measurements.
- 84681C-peptideEndogenous insulin marker$20.81
- 84681 measures C-peptide, not insulin. It may help assess endogenous insulin secretion but does not substitute for a free insulin result.
- 86337Insulin antibodiesAntibodies directed at insulin$21.41
- 86337 measures insulin antibodies. It does not measure the free insulin fraction reported with 83527.
83527 billing questions
How does 83527 differ from 83525?
83527 is for the free insulin fraction. Use 83525 when the test measures total insulin rather than free insulin.
Can free and total insulin both be reported?
Yes, when both distinct assays are performed and documented.
Can 83527 be reported with an insulin antibody test?
They measure different things: free insulin and insulin antibodies. Report each when ordered, performed, and documented.
How does Medicare pay for 83527?
Medicare pays it through the CLFS using one national amount across localities, without an office-versus-facility difference. The test is paid only under the CLFS.
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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