CPT code 87181: Agar susceptibility, per antimicrobial agent2026 Medicare lab fee · Clinical Laboratory Fee Schedule
A clinical microbiology laboratory uses agar-based testing, including gradient strips, to assess an organism’s response to an individual antimicrobial agent, reported per agent.
Medicare pays $4.75 for 87181 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
$4.75
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 87181 covers
This test assesses whether a cultured organism is susceptible to an antimicrobial agent using an agar-based method. A clinical microbiology laboratory may use a gradient strip to determine the organism’s response across drug concentrations. Results help clinicians select treatment for infections when an isolate requires susceptibility testing. The agent tested may be an antibiotic, antifungal, or antiviral drug.
Report the service per antimicrobial agent tested by this method. Medicare pays 87181 only through the Clinical Laboratory Fee Schedule (CLFS). The 2026 national CLFS amount is $4.75, unchanged from 2020 through 2026. One amount applies nationwide, without locality or office-versus-facility adjustment. The physician fee schedule excludes the test by statute.
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 87181
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 87181. 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 87181 with status X (excluded by statute), so the test itself is paid only from the CLFS.
87181 on the lab fee schedule since 2020
87181 · CLFS 2026 Q4 (current)
$4.75
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.
87181 compared with similar tests
- 87184Disk susceptibilityUp to 12 agents per plate$7.48
- Use 87184 for disk-method susceptibility testing reported per plate. Use 87181 for agar-based testing, such as with a gradient strip, reported per agent.
- 87186Susceptibility testMicrodilution or agar dilution$8.65
- 87186 identifies the microdilution or agar-dilution service, while 87181 identifies agar-dilution testing per agent, including gradient-strip testing. Select the code that matches the specific method and service performed.
- 87187MLC susceptibilityMicrodilution or agar dilution$40.17
- 87187 is used for dilution testing that determines a minimum lethal concentration. 87181 represents agar-based susceptibility testing per antimicrobial agent.
87181 billing questions
When is 87181 appropriate?
Use it for agar-based antimicrobial susceptibility testing, including testing with a gradient strip, when the service is reported per agent. The test is generally performed on an organism recovered in culture.
How is 87181 different from disk susceptibility testing?
87181 represents agar-based testing per antimicrobial agent. 87184 represents disk-method testing reported per plate; select the code that matches the laboratory method and reporting basis.
How many units are reported?
The service is reported per antimicrobial agent tested by this method. A plate or an entire susceptibility panel is not the reporting basis for 87181.
Is 87181 paid under the physician fee schedule?
No. Medicare pays this test through the CLFS; the physician fee schedule lists it as excluded by statute.
Does Medicare pay different amounts by location or setting?
No. The CLFS amount is national and applies across localities, with no office-versus-facility 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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