Why nobody can hand you the list of applicable laboratories

The number this page carries

1,729 independent clinical laboratories billed Medicare more than $12,500 under the Clinical Laboratory Fee Schedule in CY2024. Computed 2026-08-21 on the CMS Medicare Physician & Other Practitioners by Provider file, restricted to provider type “Clinical Laboratory,” with hospital and named-chain entities removed. Every exclusion is broken out in the funnel below, not folded into the total.

And separately, from the CLIA/POS establishment file:

Why that is not a list of applicable laboratories, and cannot be made into one

The definition is at 42 CFR 414.502, and it has two revenue tests. Public data can only see one of them. The regulation requires an entity that bills Medicare Part B under its own NPI to meet both:

The low expenditure threshold is the second of those, the $12,500. That one is computable from the published payment file, and it is what the 1,729 above measures.

The majority test is the first, and it is the one that cannot be done from outside. The share depends on the composition of a single lab’s Medicare revenue, which 42 CFR 414.502 defines broadly as “fee-for-service payments under Medicare Parts A and B, prescription drug payments under Medicare Part D, and any associated Medicare beneficiary deductible or coinsurance.” CMS does not publish that composition for any NPI. It is not hard to compute. It is impossible from outside.

One carve-out worth knowing, because it changes who the $12,500 applies to: the threshold does not apply to an ADLT offered by a single laboratory, only to the other CDLTs it furnishes.

So the status is self-determined, and a lab that has never asked itself the question has no external source that will ask it for them. That is the actual gap, and it is not a data-quality problem that better scraping would fix.

The finding that surprised us: the two federal registries do not join

Both CLIA and the Medicare billing file describe clinical laboratories. Joining them looks trivial. It is not.

A name-and-state cross-match between the 60 highest-signal Medicare billers and the CLIA establishment file returned 0 matches out of 60. Tried normalized, with containment matching, and with exact string equality.

The reason, once seen, is obvious and worth stating plainly: the name a laboratory bills Medicare under is its billing entity, and the name it holds a CLIA certificate under is its establishment. Those are routinely different legal objects for the same lab. Anyone who tells you they have reconciled the two registries by name has either not tried it or is matching something else.

Practical consequence for a reader: if you are trying to work out your own status, your CLIA number will not lead you to your Medicare CLFS figure, and your Medicare figure will not lead you to your CLIA record. You need both, from your own records.

The dates, from the primary source

Section 6226 of the Consolidated Appropriations Act, 2026, enacted 2026-02-03, set the current cycle: the data reporting period ran May 1, 2026 to July 31, 2026, based on a data collection period of January 1, 2025 to June 30, 2025.

That window is closed. A lab reading this in late 2026 is not looking at a deadline it can still meet; it is looking at a question about a period that has already ended. This page does not manufacture urgency it cannot support.

What this page will not tell you

1. Whether you are an applicable laboratory. The majority test is not computable from public data. Any site that tells you your status from your NPI alone is guessing.
2. Whether you were required to report for this cycle. Same reason.
3. Which named labs are in the 1,729. The figure is a count. The chain filter is keyword-based and a subsidiary with a neutral name passes through it, so the population is approximate at its edges and says so.

What can be shown is the one half that is public. The checker at pamawatch.com/check takes an NPI and puts that lab’s own CY2024 CLFS billing next to the $12,500 threshold, and stops there. The split it is written to, proven against suggested against unknowable, is at pamawatch.com/method.

Method

Sources: CMS Medicare Physician & Other Practitioners by Provider (CY2024 payments) and the CMS CLIA/POS establishment file, both read 2026-08-21. Hospital-affiliated entities are removed by keyword and named national chains by an explicit, non-exhaustive list; both exclusion counts are printed above rather than folded in. No estimation, no imputation, no scaling: every number here is a count of rows that survived a filter.

The $12,500 figure is the statutory low expenditure threshold, not a threshold we chose.