Medicare's Biggest Billers
Published February 2026 · Updated July 2026 · 12 min read
Key Finding
The top 100 Medicare providers collected $37.9B in total payments — with clinical laboratories dominating the list.
Lab Corporations Rule Medicare
When most people think of healthcare spending, they picture hospitals and doctors. But the biggest recipients of Medicare payments are often clinical laboratories — massive corporations processing millions of tests annually.
Laboratory Corporation of America (LabCorp) and Quest Diagnostics consistently rank among the top Medicare billers, each collecting hundreds of millions annually. These aren't fraudulent charges — they reflect the sheer volume of diagnostic testing in modern medicine.
$37.9B
collected by top 100 providers
61
of top 100 are lab-related
73%
of top-100 payments go to labs
The Concentration Problem
Medicare spending is remarkably concentrated. A tiny fraction of providers account for a disproportionate share of total payments. This isn't necessarily waste — large health systems and national laboratories serve enormous patient populations. But it does raise questions about market power, pricing leverage, and whether Medicare is getting value for its money.
The top 1% of Medicare providers by billing volume account for roughly 25% of all Part B payments. That kind of concentration gives these entities enormous negotiating power and makes oversight more challenging — when a single entity processes millions of claims, errors or fraud at even a fraction of a percent translate to millions in improper payments.
Concentration by the Numbers
Top 1% of providers → ~25% of all Part B payments
Top 10% of providers → ~65% of all Part B payments
Bottom 50% of providers → ~5% of all Part B payments
1.3 million total providers billing Medicare annually
Beyond Labs: Who Else Makes the List?
While labs dominate the top of the list, other types of high-volume providers also appear:
- Large ophthalmology practices — driven by expensive anti-VEGF drug injections (Eylea, Lucentis) that cost $1,800-$2,200 per treatment
- Dialysis chains — DaVita and Fresenius dominate kidney dialysis, with individual centers billing tens of millions annually
- Radiology groups — high-volume imaging centers performing thousands of MRIs, CTs, and X-rays
- Oncology practices — cancer treatment centers administering expensive chemotherapy and immunotherapy drugs
Market Consolidation
The healthcare industry has experienced massive consolidation over the past decade. The number of independent physician practices has declined by 30% since 2014, while corporate-owned practices have grown by 40%. This consolidation concentrates Medicare billing into fewer, larger entities.
The Diagnostic Testing Explosion
Part of the reason labs dominate Medicare billing is the dramatic increase in diagnostic testing over the past two decades. Genetic testing, molecular diagnostics, and advanced biomarker panels have created entirely new categories of lab work that didn't exist 15 years ago. Each new test represents another billable service — and the volume compounds quickly across millions of Medicare beneficiaries.
The rise of "precision medicine" means more tests per patient encounter. A cancer patient who might have received one or two diagnostic tests in 2010 now routinely receives a dozen or more — genomic profiling, liquid biopsy, companion diagnostics, and pharmacogenomic testing.
The Dialysis Duopoly
Two companies — DaVita and Fresenius Medical Care — control approximately 70% of the U.S. dialysis market. Individual dialysis centers can bill Medicare $10-20 million annually per facility, and with hundreds of locations each, these chains are among the largest aggregate Medicare billers in the country.
Dialysis is particularly significant because Medicare covers virtually all dialysis patients regardless of age through the End-Stage Renal Disease (ESRD) program. This means the dialysis chains have a near-captive market — their patients can't simply switch to a competitor or go without treatment. The market concentration has drawn scrutiny from Congress, with multiple hearings examining quality of care and pricing practices.
Follow the Money
Want to see how any provider stacks up? Use our provider search tool to look up any Medicare provider by name, NPI, or specialty and see their complete billing history, payment trends, and how they compare to peers.
Oversight Challenges
When individual entities bill hundreds of millions to Medicare, oversight becomes a needle-in-a-haystack problem. CMS processes over 1 billion Part B claims annually. Even sophisticated fraud detection systems can miss patterns within legitimate high-volume billing. The distinction between "a lot of tests because they serve a lot of patients" and "a lot of tests because they're billing for unnecessary services" requires clinical-level review that automated systems struggle with.
The Private Equity Factor
Private equity firms have aggressively acquired physician practices, urgent care centers, and specialty clinics over the past decade. These acquisitions often consolidate billing under fewer entities, inflate billing volumes through corporate management practices, and prioritize revenue optimization. In some cases, PE-backed practices have been investigated for aggressive upcoding and unnecessary utilization — billing practices that maximize revenue per patient encounter.
The FTC and DOJ have increased scrutiny of healthcare consolidation, but the trend continues. As more providers are absorbed into corporate entities, the Medicare billing landscape becomes more concentrated — with fewer, larger entities controlling more of the spending.
What Changed in 2014
Before 2014, Medicare provider-level payment data was hidden from the public. The AMA had successfully blocked its release through legal challenges, arguing physician privacy. In 2014, a federal judge ruled in favor of Dow Jones (publisher of the Wall Street Journal) and CMS began publishing individual provider payment data annually.
The impact was immediate. Journalists discovered individual physicians collecting millions from Medicare. Researchers identified geographic spending variations that suggested waste. Fraud investigators gained a powerful new tool. And projects like OpenMedicare were born — making this data accessible and analyzable for everyone.
Transparency Works
Since public data release began in 2014:
Dozens of fraud cases initiated using public billing data
$2B+ in fraud identified through data analysis by researchers and journalists
1,000+ academic studies published using CMS provider data
Millions of patients now able to look up their doctor's Medicare billing
How We Built This Analysis
OpenMedicare's biggest billers analysis aggregates 10 years of CMS Medicare Provider Utilization and Payment Data (2014-2024), covering over 10 billion individual service line items across 1.3 million unique providers. We rank providers by total Medicare payments received, then analyze specialty distribution, geographic concentration, and billing patterns to provide context for the raw numbers.
The data tells a story of concentration, scale, and the tension between efficiency and accountability. Whether these big billers represent the best of modern healthcare or a system ripe for reform depends on the questions you ask.
The Ambulatory Surgery Center Boom
Ambulatory surgery centers (ASCs) have been growing rapidly in Medicare, offering outpatient procedures at lower costs than hospital outpatient departments. Some ASC chains have grown to bill tens of millions annually, appearing on the big billers list alongside labs and hospitals. ASCs typically have lower charges and markups than hospitals for the same procedures — a key argument for site-neutral payment reform.
The ASC boom reflects a broader shift in healthcare delivery: procedures that once required hospital admission are now performed outpatient, driving down facility costs while creating new billing entities that contribute to the concentration of Medicare spending.
The Medicare Advantage Blind Spot
An important caveat: this analysis covers only fee-for-service (Original) Medicare billing. Medicare Advantage plans pay providers through private contracts, and those payments are not publicly reported. As MA enrollment grows (now 54% of beneficiaries), the universe of transparent billing data shrinks. Some of the "biggest billers" may actually bill more through MA contracts than they do through fee-for-service — but we can't see that data. This is a significant blind spot in Medicare transparency.
Year-over-Year Trends
The composition of the top 100 billers has shifted over our 10-year dataset. Key trends include:
- Lab consolidation: Fewer, larger lab entities now dominate the top positions as independent labs are acquired
- Ophthalmology growth: Eye care practices have climbed the rankings as anti-VEGF drug spending has surged
- Dialysis stability: DaVita and Fresenius have maintained top-100 positions throughout the dataset
- Oncology rise: Cancer centers have moved up the rankings as immunotherapy drugs have increased per-patient spending
- Home health decline: Fraud crackdowns have reduced some home health agencies' presence on the list
The biggest billers list is a mirror of American healthcare's evolution — reflecting consolidation, specialization, and the growing dominance of high-cost drugs and diagnostics.
Methodology
This analysis aggregates CMS Medicare Provider Utilization and Payment Data from 2014-2024. We rank all providers by total Medicare payments received (the "allowed amount" — what Medicare actually paid, not what was charged). The list includes both individual providers (Type 1 NPIs) and organizational providers (Type 2 NPIs). For individual providers who appear on this list, we flag potential anomalies using our fraud detection methodology.
Data is updated annually when CMS releases new payment files, typically 18-24 months after the service year. The most recent data covers services provided through 2023.
Every provider on this list has a detailed profile page on OpenMedicare. Click any provider name to see their full billing history, specialty breakdown, geographic information, and peer comparison data.
The Accountability Promise
When taxpayer money flows through a $900+ billion program, the public deserves to know where it goes. This analysis is part of OpenMedicare's mission to make Medicare spending transparent, accessible, and accountable. Every dollar on this page came from the Medicare Trust Fund — funded by payroll taxes, premiums, and general revenue. The biggest billers may be performing essential healthcare services at massive scale. Or they may warrant closer scrutiny. Either way, the data should be visible to the public that pays for it.
Browse the full list, click any provider, and judge for yourself. The data is the data — and it's yours.
Beyond the Top 100
The top 100 is just the beginning. Our database includes billing data for all 1.3 million Medicare providers. Whether you're looking for your own doctor, researching a specialist, or investigating a billing anomaly, the data is available through our provider search. Every provider has a detailed profile showing their payments, services, specialties, peer comparisons, and trend data over 10 years.
For researchers and journalists, we offer bulk data access and API endpoints. Contact us for more information about using OpenMedicare data for investigative or academic purposes.
The Future of Big Billing
As healthcare continues to consolidate, the biggest billers will only get bigger. Hospital mergers, lab acquisitions, PE-backed practice rollups, and the growth of integrated delivery networks all point toward greater concentration of Medicare spending. Whether this concentration leads to better care through scale and coordination — or worse care through market power and reduced competition — is the defining question for Medicare policy in the decade ahead.
We'll be tracking these trends annually as new CMS data is released. Bookmark this page and check back for updated rankings.
For a deeper dive into individual providers, including fraud risk scores and peer comparisons, explore our fraud analysis hub and enhanced watchlist.
The Transparency Question
One of the most valuable aspects of Medicare's public data is the ability to see exactly who receives the most taxpayer money. Before CMS began publishing provider-level data in 2014, this information was shielded from public view under legal challenges from the American Medical Association. The AMA argued that publishing individual provider payments would violate privacy and lead to misinterpretation.
The data has proven invaluable for researchers, journalists, and watchdog organizations. Investigative reporters have used it to identify fraud, expose conflicts of interest, and hold the healthcare system accountable. Our analysis extends this mission — giving anyone the tools to explore how Medicare money flows through the system.