CPT code 86318: Infectious antibody, single-step qualitative or semiquantitative2026 Medicare lab fee · Clinical Laboratory Fee Schedule
Identifies a single-step immunoassay for qualitative or semiquantitative detection of antibodies to an infectious agent.
Medicare pays $18.09 for 86318 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
$18.09
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
- QW · CLIA-waived test
- $18.09
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 86318 covers
This code covers a single-step immunoassay that detects antibodies to an infectious agent and produces a qualitative or semiquantitative result. Reagent-strip formats are one example of the method. The assay detects antibodies rather than the infectious organism itself. Laboratories and testing sites report the result according to the assay performed.
Report this code for a qualitative or semiquantitative single-step antibody assay; use 86317 for quantitative infectious-agent antibody testing. Append modifier QW for the CLIA-waived version when performed by a site holding a CLIA certificate of waiver. Medicare pays the test under the CLFS. The 2026 national amount is $18.09 and has remained unchanged since 2020; the same amount applies across localities, with no office or facility payment difference.
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 86318
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 86318. 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 86318 with status X (excluded by statute), so the test itself is paid only from the CLFS.
CLIA-waived version (QW)
CMS also lists 86318 with modifier QW, the version labs holding a CLIA certificate of waiver bill. It pays $18.09.
86318 on the lab fee schedule since 2020
86318 · CLFS 2026 Q4 (current)
$18.09
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.
86318 compared with similar tests
- 86317Infectious antibodyQuantitative measurement$14.99
- This code is for a qualitative or semiquantitative single-step infectious-agent antibody assay; 86317 is for quantitative testing.
- 86328COVID-19 antibodySingle-step immunoassay$45.28
- Code 86328 identifies the specified SARS-CoV-2 antibody assay. This code covers the broader infectious-agent antibody assay category.
- 86308Mono testHeterophile antibody screen$5.18
- Code 86308 identifies a heterophile antibody screen; this code covers single-step infectious-agent antibody assays more broadly.
86318 billing questions
When should I report this code instead of 86317?
Use this code for a qualitative or semiquantitative single-step antibody assay. Code 86317 is for quantitative infectious-agent antibody testing.
When is modifier QW appropriate?
Append QW for the CLIA-waived version when the test is performed by a site holding a CLIA certificate of waiver.
What should the documentation identify?
Document the infectious agent tested, the single-step assay performed, and whether the result is qualitative or semiquantitative.
How does Medicare pay for this test?
Medicare pays it under the CLFS at one national amount, with no locality or office-versus-facility payment difference.
How does 86328 differ from this code?
Code 86328 identifies the specified SARS-CoV-2 antibody assay; this code covers the broader category of single-step infectious-agent antibody assays.
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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