CPT code 86161: Complement function, per component tested2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Measures functional activity of individual complement components, distinguishing component-function testing from complement antigen measurement or total complement activity.
Medicare pays $12.00 for 86161 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
$12.00
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 86161 covers
Complement proteins contribute to immune-system activity, and this laboratory test assesses how well complement components function. It measures functional activity component by component, rather than the amount of a component's antigen or total complement activity. Clinical laboratories perform and report the test for clinicians evaluating complement function; results identify the component tested and its activity.
Report one service for each component tested. Medicare pays code 86161 only through the Clinical Laboratory Fee Schedule (CLFS), at one national amount across localities and office and facility settings. The 2026 national CLFS amount is $12.00, unchanged since 2020. The code is excluded from the physician fee schedule, so Medicare payment is 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 86161
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 86161. 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 86161 with status X (excluded by statute), so the test itself is paid only from the CLFS.
86161 on the lab fee schedule since 2020
86161 · CLFS 2026 Q4 (current)
$12.00
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.
86161 compared with similar tests
- 86160Complement antigenEach component$12.00
- Choose 86160 when the test measures the amount of a complement component. Choose 86161 when it measures that component's functional activity.
- 86162CH50Total hemolytic activity$20.32
- Code 86162 measures total complement activity by CH50 testing; code 86161 measures functional activity component by component.
86161 billing questions
How does code 86161 differ from code 86162?
Code 86162 measures total complement activity by CH50 testing. Code 86161 measures functional activity component by component.
How does code 86161 differ from code 86160?
Code 86160 measures complement component antigen, or quantity. Code 86161 measures functional activity.
How many units should be reported?
Report one service for each component tested. The laboratory record should identify the component and its activity.
Is a separate physician interpretation reported with code 86161?
Medicare pays code 86161 only through the CLFS, not the physician fee schedule.
Does Medicare payment vary by locality or setting?
No. One national CLFS amount applies across localities and office and facility settings.
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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