CPT code 0404U: Thymidine kinase test, serum progression-risk assay2026 Medicare lab fee · Clinical Laboratory Fee Schedule
A serum immunoassay that measures thymidine kinase activity semiquantitatively and reports a breast cancer disease-progression risk result.
Medicare pays $322.96 for 0404U 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
$322.96
In effect since Jan 1, 2026. The same amount in every state, payment locality and setting.
- Geographic adjustment
- None
- Office vs facility
- Same
- Since 2024
- 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 0404U covers
0404U describes a breast oncology assay that measures thymidine kinase activity in serum using an immunoassay. The result is semiquantitative and reported as a risk of disease progression. The assay evaluates serum thymidine kinase activity, rather than a tissue gene-expression profile or a tumor-antigen concentration. A clinical laboratory performs and reports this laboratory test.
Report 0404U for the assay performed on serum. Medicare pays it under the Clinical Laboratory Fee Schedule at one national amount across localities, with no geographic or office-versus-facility adjustment. The 2026 national CLFS amount is $322.96, unchanged from 2024 and 2025. Medicare pays this code through the CLFS; it has no physician fee schedule payment row.
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 0404U
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 0404U. 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.
Not on the physician fee schedule
The physician fee schedule doesn’t list 0404U: Medicare pays the test only from the CLFS.
0404U on the lab fee schedule since 2023
0404U · CLFS 2026 Q4 (current)
$322.96
Unchanged since Jan 1, 2024
Every change on file
- Jan 1, 2024 · CLFS 2024 Q1MAC-priced → $322.96
13 quarterly CLFS releases on file, first CLFS 2023 Q4. A code missing from a quarter wasn’t on that release.
0404U compared with similar tests
- 81519Breast gene assay21-gene recurrence score$3,873.00
- 0404U measures serum thymidine kinase activity and reports progression risk. 81519 is a breast cancer gene-expression assay that reports a recurrence score.
- 81520Breast tumor profiling58-gene hybrid-capture assay$2,510.21
- 0404U uses serum immunoassay to measure thymidine kinase activity; 81520 is a breast cancer gene-expression assay with a genomic risk result.
- 86300Tumor markerCA 15-3 quantitative assay$20.81
- 0404U measures thymidine kinase activity. 86300 measures the breast cancer-associated antigen CA 15-3.
0404U billing questions
What specimen does 0404U describe?
It describes serum tested for thymidine kinase activity by immunoassay.
What result does the assay report?
It reports a semiquantitative thymidine kinase activity result as a risk of disease progression.
How does 0404U differ from breast cancer gene-expression testing?
0404U measures thymidine kinase activity in serum. Codes 81519 and 81520 describe breast cancer gene-expression testing with different reported results.
Does 0404U have a physician fee schedule payment row?
No. Medicare pays 0404U through the CLFS, and the code has no physician fee schedule payment row.
Does Medicare use a local payment amount for this test?
No. The CLFS amount is national and applies across localities, with no office-versus-facility adjustment.
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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