CPT code 85611: PT substitution, plasma fractions, each2026 Medicare lab fee · Clinical Laboratory Fee Schedule
This prothrombin clotting-time test uses plasma-fraction substitution and is reported for each fraction tested in the assay.
Medicare pays $3.94 for 85611 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
$3.94
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 85611 covers
Code 85611 identifies a prothrombin clotting-time test performed with plasma-fraction substitution. Report the service for each plasma fraction tested, so the unit count follows the number of fractions tested. This distinguishes it from 85610, which identifies prothrombin-time testing without the substitution detail in its code name. The laboratory reports the substitution test as a laboratory service.
Medicare pays 85611 under the CLFS, with one national amount applying across states and localities and no office-versus-facility payment difference. The 2026 national CLFS amount is $3.94, unchanged from 2020 through 2025. Medicare pays the test only through the CLFS, not through the physician fee schedule. Report units according to the plasma fractions tested.
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 85611
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 85611. 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 85611 with status X (excluded by statute), so the test itself is paid only from the CLFS.
85611 on the lab fee schedule since 2020
85611 · CLFS 2026 Q4 (current)
$3.94
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.
85611 compared with similar tests
- 85610Prothrombin timeRoutine coagulation test$4.29
- Code 85610 identifies prothrombin-time testing. Use 85611 when the test involves plasma-fraction substitution.
- 85612Viper venom timeUndiluted assay$17.49
- Code 85612 identifies a viper-venom prothrombin-time test; 85611 identifies testing with plasma-fraction substitution.
- 85613Viper venom testDiluted clotting assay$9.58
- Code 85613 identifies diluted Russell viper venom testing; 85611 identifies testing with plasma-fraction substitution.
85611 billing questions
When should 85611 be used instead of 85610?
Use 85611 when the prothrombin clotting-time test involves plasma-fraction substitution. Code 85610 identifies prothrombin-time testing without that substitution detail.
How are units counted?
Report one service for each plasma fraction tested.
Is 85611 paid under the physician fee schedule?
No. Medicare pays 85611 through the CLFS.
Does Medicare payment vary by location or setting?
No. One national CLFS amount applies across states and localities, with no office-versus-facility payment difference.
How does 85611 differ from 85612 and 85613?
Code 85611 identifies prothrombin clotting-time testing with plasma-fraction substitution. Codes 85612 and 85613 identify viper-venom-based clotting tests.
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
Fee sheets
Put 85611 and the rest of your codes on one sheet
Your codes at your locality, with payer contracts beside Medicare.
Build my fee sheet