CPT code 81231: CYP3A5 testing, common variants2026 Medicare lab fee · Clinical Laboratory Fee Schedule
CYP3A5 gene testing analyzes common variants that can affect drug metabolism and may inform tacrolimus prescribing, including in transplant care.
Medicare pays $174.81 for 81231 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
$174.81
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 81231 covers
This test analyzes DNA for common CYP3A5 variants, including *2, *3, *4, *5, *6, and *7. CYP3A5 variation can affect enzyme expression and medication metabolism. Clinicians may consider testing when selecting or managing tacrolimus therapy, including in transplant care. A molecular laboratory performs the analysis.
Report 81231 for CYP3A5 common-variant analysis; it represents the gene analysis, not a separate line for each variant assessed. Medicare pays the test through the CLFS, which has one national amount across localities and no office-versus-facility payment difference. The 2026 national CLFS amount is $174.81, unchanged since 2020. The test is excluded from the physician fee schedule and paid 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 81231
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 81231. 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 81231 with status X (excluded by statute), so the test itself is paid only from the CLFS.
81231 on the lab fee schedule since 2020
81231 · CLFS 2026 Q4 (current)
$174.81
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.
81231 compared with similar tests
- 81230CYP3A4 gene testCommon variants$174.81
- 81230 evaluates CYP3A4 variants; 81231 evaluates CYP3A5 variants. Use the code corresponding to the gene analyzed.
- 81225CYP2C19 testCommon variants$291.36
- 81225 evaluates CYP2C19 common variants, not CYP3A5. These are distinct gene analyses, so select the code for the test performed.
- 81226CYP2D6 testingCommon CYP2D6 variants$450.91
- 81226 evaluates CYP2D6 common variants. It is not a substitute for CYP3A5 analysis.
- 81227CYP2C9 testCommon variants$174.81
- 81227 evaluates CYP2C9 common variants, whereas 81231 is specific to CYP3A5.
81231 billing questions
When is CYP3A5 testing relevant to tacrolimus treatment?
Clinicians may use results to understand CYP3A5-related differences in tacrolimus metabolism and inform prescribing, particularly in transplant care.
How is 81231 different from 81230?
81231 analyzes common variants in CYP3A5; 81230 analyzes common variants in CYP3A4. Select the code matching the gene analysis performed.
Should each CYP3A5 variant be billed as a separate unit?
The code represents the CYP3A5 common-variant analysis, rather than a separate service for each variant included in the analysis.
Does Medicare pay 81231 under the physician fee schedule?
No. The test is excluded from the physician fee schedule and is paid through the CLFS.
Does the CLFS amount vary by locality or setting?
No. Medicare uses one national CLFS amount for the code across localities, with no office-versus-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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