CPT code 83945: Oxalate test, oxalate-specific assay2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures oxalate when an oxalate-specific laboratory test is ordered, rather than as part of a broader organic-acid profile.
Medicare pays $14.45 for 83945 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
$14.45
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 83945 covers
CPT 83945 identifies a laboratory assay that measures oxalate. It is specific to oxalate, not a broader organic-acid profile. The laboratory reports the result for the oxalate assay performed. This code is distinguished from organic-acid tests that measure total acids, qualitatively assess organic acids, or quantify a single organic acid without specifically identifying oxalate.
Medicare pays 83945 only through the CLFS. The 2026 national CLFS amount is $14.45 and has remained unchanged from 2020 through 2026; one amount applies in every state and locality, with no geographic adjustment or office/facility payment difference. The test is excluded from the physician fee schedule by statute, so it has no separate physician-fee-schedule payment for interpretation.
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 83945
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 83945. 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 83945 with status X (excluded by statute), so the test itself is paid only from the CLFS.
83945 on the lab fee schedule since 2020
83945 · CLFS 2026 Q4 (current)
$14.45
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.
83945 compared with similar tests
- 83918Organic acidsTotal quantitative$23.60
- 83945 identifies an oxalate measurement. Code 83918 is for quantitative testing of total organic acids.
- 83919Organic acidsQualitative, each specimen$16.45
- 83945 identifies an oxalate assay; 83919 describes qualitative organic-acid testing.
- 83921Organic acidSingle analyte, quantitative$21.21
- 83921 covers quantitative testing of a single organic acid generally. Use 83945 when the assay specifically measures oxalate.
83945 billing questions
How is 83945 distinguished from organic-acid testing?
Use 83945 when the assay measures oxalate specifically. Codes for total, qualitative, or single-organic-acid testing describe different analyses.
Does 83945 represent a broad organic-acid profile?
No. It identifies an oxalate assay, not a broader organic-acid profile.
What should the documentation identify?
Documentation should identify the oxalate assay performed.
Is a physician interpretation separately payable?
No separate physician-fee-schedule payment applies; Medicare pays this test through the CLFS.
How does Medicare pay this test?
Medicare pays 83945 through the CLFS at one national amount that applies 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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