The Centers for Medicare & Medicaid Services said September 21 that Medicare has been paying about 16 percent more for laboratory services than private insurers pay for the same tests, and the agency proposed preliminary 2027 payment rates built to close that gap. CMS estimates the realignment would save taxpayers an estimated $1 billion annually once it takes full effect. The numbers are not final: they open a 30-day public comment window, and a federal law limiting how fast Medicare can cut any single lab payment means the adjustment will phase in gradually rather than all at once. The tension sits between a quick fix and a legal floor built to slow the pace.
Where the 16 Percent Gap Came From
Congress built the framework behind this month’s numbers in 2014, when the Protecting Access to Medicare Act moved CMS away from locally set fee schedules and toward pricing laboratory tests off what private insurers actually pay for the same codes. Lawmakers wrote in periodic data collection so Medicare’s rates would keep tracking the private market over time, but legislative delays meant that process ran only once, in a cycle that became the basis for 2018 rates. This year’s exercise, revived after Congress reset the reporting calendar in the Consolidated Appropriations Act, 2026, is only the second full cycle the program has completed in its history.
Participation in the second cycle grew sharply against the first. CMS says 6,411 laboratories submitted private-payor data this round, more than triple the 1,942 that reported nine years earlier, and the agency used 6,304 of those submissions after screening out duplicate records and outliers priced more than 100 times the current rate. Hospital-based labs accounted for just 21 reporters in the first cycle and climbed to 875 this time, a shift CMS traced partly to 2019 rule changes letting hospitals report Medicare revenue differently. Of 1,947 billing codes reviewed, CMS calculated a weighted median private-payor rate for 1,528 of them, or about 78.5 percent, and found that Medicare has been paying about 16 percent more for laboratory services than private payors on average across that set.
CMS Administrator Dr. Mehmet Oz framed the release as a correction rather than a routine update, saying taxpayers and Medicare patients “have been paying excessive rates to labs for years” and that the agency, “with some help from Congress,” is working to ensure Medicare “isn’t paying more than private insurers for the exact same tests.” Oz said publishing the preliminary numbers gives the public visibility into actual market rates and supports pricing decisions that extend beyond Medicare into Medicaid and Affordable Care Act exchange plans. CMS put an estimated $1 billion in annual savings on the realignment once the new rates are fully phased in.
Inside the kit: 51 state Medicare cost-help packs, the new Part D out-of-pocket cap, the prior-authorization appeal steps and a medication and cost tracker. Open The Medicare Cost & Coverage Protection Kit.
A Legal Floor Slows How Fast Rates Can Fall
The private-payor data did not point in one direction for every code. Of the 1,528 codes with a calculated weighted median, 186 came back higher than the current Medicare rate, 169 landed exactly even, and 1,171 — the large majority — came in lower, which is what pulls the overall average down to roughly 16 percent. The size of the potential change also varies sharply by category: chemistry tests average about 16 percent lower, microbiology and immunology tests average about 19 percent lower, molecular pathology tests about 22 percent lower, and genomic sequencing tests about 23 percent lower, while proprietary laboratory analyses move only about 2 percent.
Even with the private-payor math pointing sharply lower for most categories, federal law caps how quickly CMS can act on it. Under a phase-in that runs from calendar years 2027 through 2029, Medicare cannot cut payment for any single clinical diagnostic laboratory test by more than 15 percent in one year compared with the prior year’s rate, regardless of how large the gap to the private-sector benchmark turns out to be. A test whose private-payor price sits 40 percent below its current Medicare rate would need roughly three annual cuts to close that gap, not one. The statute treats the private-payor benchmark as a target CMS phases toward rather than a number it can apply in a single step.
That phase-in schedule was itself part of this year’s legislative activity. The Consolidated Appropriations Act, 2026 both revived the stalled data-reporting cycle and wrote the three-year phase-in into law, a combination CMS says lets it correct outdated rates without an abrupt one-year shock to laboratories that depend heavily on Medicare billing. The agency is also publishing the preliminary rates with and without certain excluded records and asking for public comment on whether that exclusion method is the right one to use when the final weighted medians are calculated.
Preliminary Numbers, a Comment Window, and a January Start
Every figure in this release carries a preliminary label, and CMS said plainly that final rates will not be published until later in the year. The 30-day comment period opened the same day as the announcement, September 21, and covers both the preliminary weighted-median rates and the underlying data files CMS posted alongside them. Written comments go to the agency’s dedicated CLFS email box, and CMS has not indicated it will extend or shorten that window before rates are finalized.
A separate track covers existing codes for which no laboratory reported usable private-payor data this cycle. CMS held a public meeting on September 15 and 16 where an expert panel of laboratory professionals recommended how those codes should be priced, either by crosswalking them to a comparable test already on the fee schedule or by gapfilling a rate through other methods. CMS said it will publish its determinations for those codes in early October, opening a second 30-day comment period that runs separately from the one already covering the codes with private-payor data in hand.
CMS said it expects to finalize the full set of CY2027 Clinical Laboratory Fee Schedule payment rates in November 2026, after both comment periods close and the agency reviews the public record. The rates are scheduled to take effect January 1, 2027, leaving laboratories, Medicare contractors and CMS itself roughly two months between finalization and implementation. Until that November publication, the 16 percent gap, the $1 billion savings estimate and every category-level figure in this release remain what CMS itself calls preliminary — numbers built for public review, not yet the rates Medicare will actually pay.
Lab Bills and the Appeal Route
None of this preliminary rate math changes what happens when a lab bill already arrives with a code Medicare or a Medicare Advantage plan disputes, or when a claim gets kicked back for a prior authorization that was never filed. CMS’s proposal addresses what the agency pays laboratories, not what a beneficiary does when a bill looks wrong or an appeal deadline is closing in. That gap between the policy story and the paperwork sitting in someone’s mailbox is where most of the actual confusion happens.
The Medicare Cost & Coverage Protection Kit is a 10-page kit built around 51 state Medicare cost-help packs and the prior-authorization appeal steps laid out in order.
See The Medicare Cost & Coverage Protection Kit.
This article was researched and drafted with the assistance of AI and reviewed by The Money Overview editorial team.
