Clinical Laboratory Fee Schedule and PAMA

Medicare Part B pays for clinical diagnostic laboratory tests from one national list, the Clinical Laboratory Fee Schedule (CLFS). Section 216 of the Protecting Access to Medicare Act of 2014 (PAMA) changed how that list is set: since January 1, 2018, rates rest on "the weighted median of private payor rates" (81 FR 41036). Before PAMA, CMS says, a test was generally paid the lesser of the billed charge, the contractor's fee schedule or a national limitation amount (CMS fact sheet).

Three consequences follow from the regulation. A rate is national: it is "not subject to any adjustment, such as geographic, budget neutrality, annual update, or other adjustment" (§ 414.507(c)). It holds for three calendar years for most tests and one year for advanced diagnostic laboratory tests (§ 414.507(a)). And a test with no private payor data is priced by crosswalking to a similar test or, failing that, by gapfilling, where the MACs develop the amount (MLN006818).

What the 2026 schedule pays for tests a small lab runs every day:

CMS fee file 26CLABQ4 (CY 2026, quarter 4), read 2026-10-23. The collection fee is paid in addition to the test (CPT 36415).

Drug testing shows the spread inside one schedule. The definitive tiers run from G0480 at $114.43 for 1 to 7 drug classes up to G0483 at $246.92 for 22 or more, and a presumptive cup read by eye (80305) pays $12.60. If you bill those, our toxicology LIS comparison covers the systems that track them.

CMS posts the schedule as a downloadable file on its CLFS files page and replaces it each quarter. The one in force today is 26CLABQ4, the fourth quarter of 2026, which "includes all changes identified in CR 14569"; MLN Matters MM14569 explains that update in plain words. The file lists 2,117 codes on 2,243 lines: a code that has a waived version appears twice, once plain and once with the QW modifier at the same rate (how QW works).

Each line carries the year, the HCPCS code, any modifier, the effective date and the rate. The descriptors in the file are CPT text under AMA copyright, which is why lab price lists and billing systems keep the code and write their own names. Medicare Advantage plans and commercial payers set their own fees, so this file is Medicare Part B's price, not the market's.

PAMA turns some labs into data sources. An "applicable laboratory" must report its private payor rates; everyone else must not. Under § 414.502 it is a CLIA laboratory that bills Medicare Part B under its own NPI (a hospital outreach lab: bill type 14x), receives "more than 50 percent of its Medicare revenues" from the CLFS and the physician fee schedule, and receives "at least $12,500 of its Medicare revenues" from the CLFS. CMS's quick reference guide for physician office labs (April 2026) turns that into five questions. One "no" ends it: not an applicable lab, do not report.

Question 1 counts a certificate of waiver. Unsure which certificate your lab holds or needs? The CLIA certificate finder answers it from the test menu, and how to get a CLIA certificate walks through applying.

Five yeses and the lab is applicable and must report. For a practice whose lab shares the group NPI, physician fee schedule revenue counts in the numerator, so the majority test rarely screens it out and the $12,500 floor does the real sorting.

What gets reported is "applicable information": each private payor rate for which final payment was made in the data collection period, the volume paid at that rate, and the HCPCS code, leaving out capitated payments. Private payors are health insurers, group health plans, Medicare Advantage plans and Medicaid managed care plans. The reporting entity is the TIN-level organization, and its President, CEO or CFO, or a delegate who reports to one, signs a certification that the data are "accurate, complete, and truthful" (§ 414.504(d)).

CMS's summary of the current law: "On February 3, 2026, Section 6226 of the CAA, 2026 was passed". It moved the data collection period to January 1–June 30, 2025 and the reporting period to May 1–July 31, 2026, which has now ended. "There's no phase-in reduction in 2026. Beginning January 1, 2027 - 2029, payment may not be reduced by more than 15% percent per year" (CMS CLFS page). Rates are then updated every three years.

On September 21, 2026 CMS posted preliminary 2027 rates built from that report:

Of the codes with a median, 1,171 came in lower than today's rate, 169 equal and 186 higher. The 15% cap turns a deep drop into a three-year walk down. A made-up example: a test paying $20.00 in 2026 whose new median is $12.00 can fall to $17.00 in 2027, $14.45 in 2028 and $12.28 in 2029, each step 15% below the year before.

• Decide applicable status in writing for every data collection period, with the revenue figures behind each of the five answers kept on file.
• Watch the final 2027 rates. The preliminary medians are posted on the CLFS & PAMA reporting page; the 15% cap limits how far any one code moves in a year.
• Keep the fee tables current. A billing system that prices from an old quarter can misprice new codes and miss QW lines. Ask how vendors load the quarterly file in lab billing software compared and XiFin vs TELCOR, or what an outside firm handles in lab billing companies compared.