National MolDX Expansion: What Labs Need to Know in 2026
Short answer: CMS is actively considering requiring every clinical laboratory in the country to register its molecular and genetic tests with the MolDX program before billing Medicare. The idea appeared in the agency's February 27, 2026 CRUSH Request for Information. It is not a rule yet — but the claims data, the enforcement trend, and payer behavior all point the same direction, and labs in non-MolDX jurisdictions should prepare now.
If your lab bills Medicare in a Novitas, First Coast, or NGS jurisdiction, you have never needed a DEX Z-Code to get a molecular test paid. That assumption is now under review. This guide covers what CMS actually proposed, the numbers behind it, how the industry responded, and the concrete steps labs can take before any rule is written.
What MolDX is today — and where it applies
The Molecular Diagnostic Services Program (MolDX) was established in 2011 and is administered by the Medicare Administrative Contractor (MAC) Palmetto GBA. It is also used by the MACs Noridian, CGS, and WPS. Together those contractors cover roughly 28 states.
Inside a MolDX jurisdiction, a lab cannot simply bill a molecular test and expect payment. It must register the test in the DEX Diagnostics Exchange, obtain a unique Z-Code identifier, and — for many tests — complete a technical assessment demonstrating analytical validity, clinical validity, and clinical utility. Until a covering Local Coverage Determination (LCD) exists, the test is effectively non-covered; there is no claim-by-claim reimbursement pathway in the interim.
The other 22 states operate on what the industry calls a pay-first model: claims are adjudicated on submission and audited retroactively. That structural gap is the entire subject of the current policy debate. For a fuller walkthrough of how NCDs, LCDs, and the DEX registry interact, see our guide to Medicare coverage for genetic testing.
Why CMS is looking at national expansion
Two things happened in quick succession at the start of 2026.
First, on January 28, 2026, the HHS Office of Inspector General released its annual analysis of Medicare Part B lab spending. Part B spending on lab tests rose 5% in 2024 to $8.4 billion, despite no changes to the Clinical Laboratory Fee Schedule since 2020. The headline finding was the concentration: genetic testing accounted for 43% ($3.6 billion) of total Part B lab spending while representing only about 5% of tests paid — a roughly $600 million increase year over year, against essentially flat non-genetic reimbursement. In 2018, genetic testing was 18% of that spending.
Second, on February 27, 2026, CMS published a Request for Information in the Federal Register under a new initiative called CRUSH (Comprehensive Regulations to Uncover Suspicious Healthcare). Among the ideas floated: requiring nationwide registration with the MolDX program. Comments closed March 30, 2026.
An RFI is not a proposed rule. Any binding requirement would need a separate proposed rule with its own comment period — and CMS has published no timeline.
The CPT 87798 signal: what the claims data shows
The clearest evidence that jurisdiction shapes billing behavior sits in a single code. CPT 87798 is the catch-all for infectious-agent detection by nucleic acid when no organism-specific code exists — respiratory panels, UTI panels, wound-infection workups.
An analysis of Medicare fee-for-service claims published by MedScout in April 2026 found that 87798 volume nearly doubled in non-MolDX regions, from roughly 694,000 to 1.3 million claims, while staying essentially flat in MolDX regions. The number of labs billing the code moved the same way: from 402 to 501 in pay-first regions, and from 435 down to 358 in MolDX regions. Two contractors — Novitas and First Coast — accounted for nearly all the growth. Texas alone grew 244%, from about 165,000 to 569,000 claims.
This pattern has a precedent. CPT 81408, used for rare-disease sequencing, followed the same trajectory in permissive jurisdictions until an OIG audit flagged $888 million at risk of improper payment on that single code in 2023. Contractors tightened, denials rose, and volume collapsed.
Labs are already feeling the tightening on 87798: denials have spiked consistently since mid-February 2026. Because lab margins are thin, a 10% reimbursement cut is generally understood to translate into a 3–4 point drop in profit margin. If you are seeing an unexplained rise in molecular denials, our breakdown of why genetic testing claims get denied maps the six failure modes worth auditing first.
How the industry responded
Public comments, reported by 360Dx on April 30, 2026, split along a clear line: laboratories and pathologists largely opposed expansion; payers largely supported it.
Opposed
The Association for Molecular Pathology (AMP) said the cost, time, and resource burden of securing Z-Codes and completing technical assessments has been significant for its members. The Healthcare Business Management Association called MolDX registration "extremely expensive, complex and time-consuming, often putting it out of reach for innovative, independent laboratories." The National Independent Laboratory Association warned that registration timelines would delay patient care. ACLA, the AMA, the College of American Pathologists, and MD Anderson also opposed.
The common counter-proposal: MACs should use claims analytics earlier — flagging atypical utilization patterns, sudden volume spikes, and billing disconnected from clinical context — rather than adding a registration gate that burdens compliant labs. ACLA separately pressed for transparency on MolDX coverage timelines, noting some requests have stalled for more than two years.
More open
Advanced-diagnostics firms, particularly single-site labs with proprietary tests, were more receptive. Natera said MolDX has "contributed to improved payment accuracy" and helped distinguish clinically appropriate testing from low-value services, while cautioning that a national rollout should be phased. The Coalition for 21st Century Medicine and AdvaMed did not oppose expansion outright but asked for guaranteed decision timelines and a formal dispute-resolution mechanism.
Payers
UnitedHealthcare urged CMS to adopt "structured identifiers and quality oversight for genetic testing (including expanded use of MolDX-type frameworks)." Elevance, Highmark, and Devoted Health were similarly supportive. Notably, UnitedHealthcare already requires MolDX Z-Codes for some molecular tests — meaning commercial adoption of the framework is proceeding regardless of what CMS decides.
What national MolDX would actually change for a lab
For a lab currently operating in a pay-first jurisdiction, four things change materially:
1. Registration becomes a prerequisite, not a formality. Every molecular or genetic test billed to Medicare would need a DEX Z-Code before the first claim.
2. Technical assessments become a resourced function. TA submissions require evidence of analytical validity, clinical validity, and clinical utility — work that requires scientific writing capacity most small labs do not have on staff.
3. Revenue timing shifts. A test with no governing LCD is non-covered until one exists. Under a national program, launching a new assay means budgeting for a coverage gap rather than billing from day one.
4. Non-specific codes lose their utility. Codes like 87798 and 81408 exist because specific ones do not. A registration regime pushes labs toward precise test identification — and several commenters, including ACLA, asked CMS to create more specific CPT codes for exactly this reason.
Five things labs can do now
Inventory your molecular menu against Z-Code status. For each test you bill to Medicare, record whether a DEX Z-Code exists, whether a technical assessment has been submitted, and which LCD (if any) governs it. Labs already in MolDX jurisdictions have this; pay-first labs usually do not.
Audit your non-specific code usage. Pull your 87798 and 81408 volume by month. If either has grown sharply without a matching change in test menu or referral pattern, that is the profile contractors are targeting.
Tighten medical-necessity documentation upstream. Under any MolDX-style regime, the diagnosis-to-test link is scrutinized before payment rather than after. Our ICD-10 coding guide for genetic testing covers the code families payers expect and the vague ones that trigger denials.
Check your commercial contracts for Z-Code language. UnitedHealthcare already requires Z-Codes on some molecular tests. Commercial requirements may bind you before CMS does.
Build the technical-assessment capability before you need it. If expansion happens, every unregistered lab will queue at once. Labs with validation dossiers already assembled will clear faster.
Frequently asked questions
Is MolDX going national?
Not yet. CMS raised nationwide MolDX registration as an option in its February 27, 2026 CRUSH Request for Information, with comments due March 30, 2026. An RFI gathers input only. Any requirement would need a separate proposed rule and comment period, and CMS has announced no timeline.
Which states are currently in MolDX?
MolDX is administered by Palmetto GBA and used by the MACs Noridian, CGS, and WPS, covering roughly 28 states. The remaining 22 states are served by Novitas, First Coast Service Options, and NGS, which do not require MolDX test registration before billing.
Why are CPT 87798 claims being denied in 2026?
Labs across the U.S. have reported a consistent spike in 87798 denials since mid-February 2026, coinciding with heightened CMS scrutiny of molecular billing. Claims data shows 87798 volume nearly doubled in non-MolDX jurisdictions while staying flat in MolDX ones — the utilization pattern contractors are now targeting.
How much does Medicare spend on genetic testing?
Per the OIG's January 2026 report, genetic testing accounted for 43% ($3.6 billion) of the $8.4 billion Medicare Part B spent on lab tests in 2024, while representing only about 5% of tests paid. That share was 18% in 2018.
What is a DEX Z-Code and would every lab need one?
A DEX Z-Code is a unique identifier assigned through the DEX Diagnostics Exchange registry that lets a MAC identify precisely which molecular test was performed. Under a national MolDX requirement, every lab billing Medicare for a molecular or genetic test would need one — plus, for many tests, a completed technical assessment — before submitting claims.
Educational disclaimer: This article summarizes Medicare coverage policy developments as of August 2026 for general informational purposes. The CRUSH RFI is a request for information, not a rule; no national MolDX requirement is in effect. Coverage policies, LCDs, MolDX requirements, and contractor jurisdictions change and vary by MAC and payer. This is not billing, legal, or medical advice. Verify against current CMS and payer policy with qualified compliance and billing professionals. ScreenMyGene is clinical decision support and does not replace independent professional judgment.
Sources: Federal Register, "Request for Information (RFI) Related to Comprehensive Regulations To Uncover Suspicious Healthcare (CRUSH)," February 27, 2026; HHS Office of Inspector General report on Medicare Part B lab test spending, January 28, 2026; 360Dx, "Clinical Lab Industry Broadly Opposes MolDX Expansion, Comments on CMS RFI Show," April 30, 2026; MedScout, "Labs face reimbursement headwinds as CMS weighs national regulation," April 28, 2026; Palmetto GBA MolDX program and DEX Diagnostics Exchange documentation; HHS OIG 2023 audit of CPT 81408.
For the platform these guides support, see ScreenMyGene: genetic-test decision support.