Medicare Clinical Laboratory Fee Schedule (CLFS): How Lab Payment Works
Medicare Part B pays most clinical diagnostic laboratory tests (CDLTs) under the Clinical Laboratory Fee Schedule (CLFS). Under PAMA, each test's rate is the weighted median of private payor rates that applicable labs report. Rates are generally updated every 3 years. For 2027 through 2029, CMS says a test's rate can't fall more than 15% per year.
Sound Lab Consultants (SLC) provides clinical lab billing and compliance support nationwide. This page summarizes CMS sources. It does not quote any rates. For current amounts, use the CMS CLFS files.
What the CLFS is
The CMS Clinical Laboratory Fee Schedule page explains that Medicare pays most CDLTs based on the weighted median of private payor rates. The Protecting Access to Medicare Act (PAMA) requires this method. The rates come from data that labs collect during a data collection period and then report to CMS.
The regulation is 42 CFR 414.507:
The rate is the weighted median of private payor rates, weighted by volume for each payor and each lab.
Rates stay in effect for 3 calendar years for most CDLTs and 1 year for ADLTs.
Rates get no geographic, budget-neutrality, or annual update adjustment.
For "private payor," CMS includes health insurance issuers, group health plans, Medicare Advantage plans, and Medicaid managed care organizations.
The PAMA data cycle
CMS describes three steps. Labs collect data during the collection period, analyze whether they meet the applicable-laboratory thresholds, and report through their reporting entity. According to the CMS CLFS page:
The latest reporting period ran May 1 to July 31, 2026, using data collected January 1 to June 30, 2025. Section 6226 of the Consolidated Appropriations Act, 2026 (passed February 3, 2026) set those dates.
There is no phase-in reduction in 2026.
For 2027 through 2029, a test's payment may not drop more than 15% per year compared with the prior year.
After 2026, CDLTs (other than ADLTs) follow a 3-year reporting cycle.
CMS has posted preliminary CY 2027 CLFS data and a fact sheet. For who has to report, see PAMA reporting for clinical laboratories.
Note: The eCFR text of § 414.504 and § 414.507 may not yet show the CAA 2026 changes. Use the CMS pages for current dates and caps.
ADLTs and new tests
Advanced diagnostic laboratory tests (ADLTs) are a CDLT subcategory created by Section 1834A of the Social Security Act. They have separate reporting and payment rules, and ADLT rates are reset every year. CMS keeps a list of ADLTs and an application for ADLT status on its ADLT information page. New CDLTs are priced through the public consultation process in §§ 414.506–414.509, which includes the CLFS annual public meeting and the CLFS Advisory Panel.
Cost-sharing, specimen collection, and travel
No deductible or coinsurance: Medicare Claims Processing Manual, Chapter 16, § 30.2 says the Part B deductible and 20% coinsurance don't apply to clinical lab tests paid on an assigned basis. They also don't apply to specimen collection fees or travel allowances.
Specimen collection fee and travel allowance: 42 CFR 414.523 sets a specimen collection fee for specimens a trained technician collects from homebound patients or non-hospital inpatients. The amount is updated each year. It also sets a travel allowance. Check the current CLFS files for the amounts.
Where to find current CLFS rates
CMS CLFS files: quarterly and annual files.
CMS CLFS history: background on the fee schedule.
CMS Clinical Labs Information Center: CMS's central hub for lab payment, coverage, coding, and manuals.
Your Medicare Administrative Contractor (MAC): local billing guidance.
CLFS checklist for labs
☐ Load each year's CLFS file (and the quarterly updates) into your billing system.
☐ Confirm every test's HCPCS/CPT code, and any QW modifier for waived tests.
☐ Decide whether your lab is an applicable laboratory for PAMA reporting.
☐ Plan for the 15% annual cap on rate reductions in 2027–2029 when you budget.
☐ Make sure no deductible or coinsurance is charged for assigned CLFS tests.
☐ Track ADLT or new-test pricing notices if you offer new assays.
☐ Subscribe to MLN Connects for CLFS updates.
FAQs
How does Medicare set lab test prices?
Under PAMA, the CLFS rate for most tests is the weighted median of private payor rates reported by applicable labs (42 CFR 414.507).
How often does the CLFS change?
CMS generally updates private-payor-based rates every 3 years. ADLT rates are updated every year, and CMS also posts quarterly files.
What changes in 2027?
CMS says that for 2027–2029, a test's payment can't be cut more than 15% per year from the prior year. The rates are based on data reported in 2026.
Do patients pay coinsurance for lab tests?
Not for clinical lab tests paid under the CLFS on an assigned basis. Claims Processing Manual Ch. 16 § 30.2 says the deductible and coinsurance don't apply.
Are CLFS rates adjusted by location?
No. Under § 414.507(c), CLFS rates aren't adjusted geographically.
Where do I get the official rates?
From the CLFS files on CMS's website. SLC doesn't publish rate tables.
Get help with lab billing
SLC offers clinical lab billing and medical billing services along with CLIA compliance. See also Medicare lab billing basics and lab NCDs and LCDs.
Sound Lab Consultants Mailing address: PO Box 2135, Chandler, AZ 85244