A denied claim is rarely a zero. It is the cost of running the test, plus the staff hours spent figuring out why it bounced, plus the appeal that may or may not happen, plus the write-off if it does not. For a molecular or genetic lab, where a single comprehensive panel can carry a four-figure charge, denials are not a back-office annoyance. They are a direct hit to margin, and the data says the hit is getting bigger.
Disclaimer: This is educational, not billing, legal, financial, or medical advice. Payer policies, coverage criteria, and reimbursement rates change frequently, and your situation may differ from the examples here. Always verify current requirements against the payer's most recent published policy and consult qualified billing, compliance, or financial professionals. Use this information at your own risk.
The size of the problem, in numbers you can trust
Start with the most rigorous evidence available. A 2025 cohort study in JAMA Network Open, run by Georgetown University researchers and funded by the National Cancer Institute, looked at 29,919 cancer-related next-generation sequencing (NGS) claims across 24,443 Medicare beneficiaries. It found that 23.3% of those claims were denied between 2016 and 2021.
That is the headline, but the trend underneath it is the part worth sitting with. The denial rate was 16.8% before Medicare's National Coverage Determination for NGS (NCD 90.2) took effect, 20.3% after it was implemented in 2018, and 27.4% after it was amended in 2020. Coverage expanded across that window. Denials climbed anyway. More on why that happens below, because it is the most important thing in this article.
Outside of Medicare, the picture is at least as difficult. XiFin's 2024 Payor Denial Impact Report, drawn from more than 20 million laboratory claims, reports that roughly 35.3% of billed molecular CPT codes are denied (this is industry data rather than peer-reviewed research, but it is directionally consistent with the Medicare findings).
Now attach a dollar figure. In the JAMA Network Open study, the median charge on a denied NGS claim was $3,800, which the authors frame as the upper limit of provider or patient liability for each denial. Multiply that exposure by a denial rate in the twenties or thirties, across your annual volume, and the denial line stops looking like a rounding error and starts looking like a strategic problem.
Denials are a margin problem wearing a billing costume
It is tempting to treat denials as something the billing team handles. The economics say otherwise.
Every denied claim consumes the same reagents, instrument time, and labor as a paid one. The difference is that a denied claim then adds cost: someone has to read the remittance, identify the reason code, decide whether to rework or appeal, assemble documentation, and resubmit. That work is incurred whether or not the dollars are ever recovered. A high denial rate is therefore a double charge against margin, the cost of the unreimbursed test plus the cost of chasing it.
And here is the quietly expensive part. A 2025 Health Affairs study from UCSF researchers found that 46% of appealed genetic-testing denials were overturned through independent medical review between 2019 and 2023. Yet the same study found that fewer than 1% of denials are appealed through that process. Read those two figures together and the implication is uncomfortable: nearly half of the genetic-testing denials that get challenged are reversed, and almost no one challenges them. The reversible revenue is sitting there. Most labs simply do not have the capacity to go get it, so they triage, pursue the cleanest cases, and write off the rest.
That capacity ceiling is the real cost. It is not just the claims you lose; it is the claims you could win but never reach.
Where you sit changes how much you bleed
The denial burden is not distributed evenly, and the JAMA Network Open study is unusually specific about who carries the most of it. Claims for NGS testing were more than twice as likely to be denied when performed by an independent laboratory (odds ratio 2.76) or another non-hospital site (odds ratio 2.55) than when performed by a hospital. For independent labs specifically, the NGS denial rate reached 37.3% in the most recent period the study examined.
Panel size compounds it. The study found that claims for 50 or more genes were more likely to be denied than smaller panels for solid tumors. So the lab profile most exposed to denials is precisely the one defining modern oncology diagnostics: an independent molecular lab running large, comprehensive panels. If that describes you, the denial rate is not a billing statistic. It is a structural feature of your business model that you have to actively manage.
The driver almost everyone misreads
Return to the trend that should bother you most: as Medicare broadened NGS coverage in 2018 and again in 2020, the denial rate rose, from 16.8% to 27.4%. If coverage expanded, why did denials go up?
Because coverage and payability are not the same thing. A test can be covered in principle and still be denied in practice if the claim does not satisfy every specific condition the policy attaches to that coverage. Each expansion of NCD 90.2 came with more criteria, the right cancer stage, the right prior-testing history, the right ordering context, the right documentation. Every additional requirement is another edge a claim can fall off. Broader coverage written as more detailed rules produces more denials, not fewer, unless the lab keeps perfect pace with the rules.
This is the throughline connecting every denial statistic in this article. The dominant cause of molecular denials is not payers refusing to cover good tests. It is the widening gap between what current policy requires and what the claim actually reflects. And that gap is fed by constant change. Consider just the moving pieces from the last two years:
- The MolDX program made the DEX Z-Code a hard gate. Since May 1, 2025, MolDX claims submitted without the Z-Code in the correct claim loop deny as unprocessable (per Noridian guidance), with no clinical review at all.
- UnitedHealthcare extended a DEX Z-Code requirement to its commercial molecular claims, announced for April 1, 2024 and then delayed to June 1, 2024, with claims denied when the Z-Code is missing, invalid, or mismatched.
- The federal prior-authorization rule (CMS-0057-F) is changing payer decision timelines, requiring 72-hour turnarounds for expedited requests and 7 calendar days for standard ones as of January 1, 2026, with new API requirements arriving in 2027.
None of those is exotic. They are the normal cadence of payer policy change, and each one quietly rewrote the conditions a clean claim has to meet. A lab that did not catch each change inherited a new denial pattern it did not choose.
The leadership math (without the fake numbers)
It would be easy to drop a tidy ROI figure here. The honest version is more useful: the economics of denials hinge on two ratios that are within your control.
The first is prevention versus rework. A denial caught before submission, a missing Z-Code added, a diagnosis code positioned correctly, a test name populated on an unlisted code, costs a fraction of the same denial caught after the fact, which carries remittance review, appeal assembly, and resubmission on top. The cheapest denial is the one that never happens, and most molecular denials are operational, which means they are preventable at the rule-and-scrub stage rather than the appeal stage.
The second is the 46%-versus-1% gap. Every denial you do not appeal is a coin-flip-or-better you declined to take. You will never appeal everything, and you should not try, but the distance between a 1% appeal rate and a defensible one is pure recovered margin.
Both ratios improve from the same root capability: knowing, precisely and currently, what each payer requires for each test and indication, and applying that knowledge before the claim goes out the door. That is not a billing function. It is a policy-operations function, and most labs do not have one.
The strategic takeaway
The molecular denial problem is often described as a coding problem or a payer problem. It is more accurate to call it a change-management problem. Coverage rules move constantly, across Medicare NCDs and LCDs, MolDX requirements, and dozens of commercial medical policies, and the denial rate is essentially a measure of how far your claims have drifted from the current rules.
That reframing matters because it points to a durable fix. You cannot stop payers from changing their policies, and you cannot hire your way to perfect coverage of every change with spreadsheets and tribal knowledge. What you can do is treat payer policy as living data: tracked at the source, translated into the specific rules that govern each test and indication, and kept current automatically so that the claim reflects today's requirements instead of last year's. Keeping that rule layer accurate, per payer, per test, per indication, is exactly what turns a 23% denial rate into a recoverable one, and it is the problem Converus was built to solve.
Sources
- Claim Denials for Cancer-Related Next-Generation Sequencing in Medicare — JAMA Network Open, April 18, 2025 (doi:10.1001/jamanetworkopen.2025.5785; PubMed 40249617)
- Use of Independent Medical Review: Almost One-Half of Coverage Denials Overturned — Health Affairs, December 2025 (doi:10.1377/hlthaff.2025.00716)
- 2024 Payor Denial Impact Report — XiFin, Inc. (analysis of 20M+ laboratory claims)
- Proper Submission of DEX Z-Code for Molecular Diagnostic Services (MolDX) Claims — Noridian Healthcare Solutions (effective May 1, 2025)
- Make Sure Molecular Tests Have a Z-Code Assigned — UnitedHealthcare (commercial Z-Code requirement, 2024)
- CMS Interoperability and Prior Authorization Final Rule (CMS-0057-F) — Centers for Medicare & Medicaid Services