Medicare Advantage penetration by county — and what it changes about your sales approach
Two counties with identical senior populations can behave completely differently for a healthcare seller, because in one the authority sits with fee-for-service Medicare and in the other it sits with a handful of Medicare Advantage plans. CMS publishes the split monthly at county level, and it is one of the highest-value free datasets in healthcare sales.
6 min read
What the file contains
By county: total Medicare eligibles, the number enrolled in Medicare Advantage, and the resulting penetration rate. Plan-level detail identifies which organizations hold the enrolled lives. Because it is monthly, trend is available rather than a single annual snapshot.
Why penetration changes the sales motion
High MA penetration concentrates decision authority. Utilization management, network inclusion and prior authorization sit with a small number of plans, so the path to volume runs through plan contracting rather than through individual clinician relationships. Low penetration disperses authority back to referring clinicians and facilities, which favours a field-based referral strategy.
The same product, the same pitch, the same rep — different county, different correct motion. Getting this backwards is a common and expensive territory error.
Example pull from RepVector
Retained Medicare Advantage and enrollment rows for a resolved county.
Medicare Advantage penetration for Philadelphia, Philadelphia County, Pennsylvania (2025)
| County | Year | Medicare beneficiaries | Original Medicare | Medicare Advantage | MA penetration |
|---|---|---|---|---|---|
| Philadelphia County | 2,025 | 265,467 | 106,977 | 158,490 | 59.7 |
| Montgomery County | 2,025 | 188,594 | 118,776 | 69,818 | 37 |
First 2 of 2 retained rows. See the full field list for Medicare Advantage penetration by county
Reading it correctly
Penetration is a rate; always carry the denominator alongside it. A 60% rate over 4,000 eligibles is a smaller opportunity than a 25% rate over 90,000. Small counties also produce volatile month-to-month rates on small bases, and CMS suppresses small cells — a suppressed value is missing, not zero, and must never be summed as zero.
What to pair it with
Medicare enrollment for the denominator, Medicare geographic variation for utilization and cost intensity, HCRIS for hospital financial position, and Medicaid enrollment for the dual-eligible picture. Together they answer whether the market can pay and who signs.
What to take away
- High penetration means the plan authorizes; low penetration means the clinician does.
- Always read the rate with its denominator.
- Suppressed small cells are gaps, not zeros.
- Monthly publication makes trend available, not just a snapshot.
Put this to work
RepVector assembles this for a named market in one query
Describe the market and the offering. The datasets above are selected, resolved to your geography, pulled, scored, and returned as a ranked list with every figure sourced.
Related guides
- HCRIS hospital cost reports: reading a hospital's financial position before you pitch it
Every Medicare-certified hospital files an audited annual cost report. It is public, and it tells you who can buy.
- How to build a healthcare territory plan you can defend
Size the universe, rank it, and set quota against a denominator instead of last year's number plus ten percent.
- Medicaid State Drug Utilization Data for market access planning
Quarterly, by state, by drug: units reimbursed and amounts paid. The clearest public read on therapeutic demand.