Where do I get Medicare enrollment data by county?

From CMS, for free, every month. Two files cover almost everything an agent needs: the MA State/County Penetration file, which lists eligible beneficiaries, Medicare Advantage enrollees, and the penetration percentage for every county, and the Medicare Monthly Enrollment dataset on data.cms.gov, which splits county totals into Original Medicare versus Medicare Advantage and adds Part D. Add the Census Bureau's 65-and-over table and you have a sourced picture of your market in twenty minutes.

Most agents look these numbers up once, for a carrier meeting, and never publish them. That's the missed opportunity. When someone asks an AI assistant about Medicare in your county, it is hunting for specific, verifiable facts about that county. "As of August 2026, [X]% of Medicare beneficiaries in this county are enrolled in Medicare Advantage, per CMS" is exactly the kind of sentence it can quote. "We've served the community for 20 years" is not.

Which CMS files have county-level Medicare numbers?

CMS keeps its Medicare Advantage and Part D enrollment reports on one hub, the MA/Part D Contract and Enrollment Data page, and says monthly updates are scheduled to post by the 15th of each month.

Two caveats. CMS suppresses very small plan-by-county cells in the plan-level file, so a tiny rural county may show fewer plan rows than exist. And enrollment figures are reconciled over time, so a month's number can shift slightly in later releases. Neither matters if you cite the month you used.

How do I read the penetration file?

1. Download the current month from the MA State/County Penetration page. You get a compressed archive containing a spreadsheet.
2. Filter to your state, then your county. Each county is one row with three columns that matter: eligibles, enrolled, and penetration.
3. Write the sentence. "As of [month year], [enrolled] of [eligibles] Medicare beneficiaries in [County], [State] were in a Medicare Advantage plan, a penetration rate of [X]%." Link the file.
4. Repeat for the plan-level file if you want carrier detail, and save the source URL and month. You need both on the page, and again when you refresh the numbers.

Why publish the numbers instead of just knowing them?

Because verifiable specifics get quoted. Google's self-assessment for helpful content asks whether a page provides "original information, reporting, research, or analysis" and "substantial value when compared to other pages in search results." A county page with sourced enrollment figures clears both bars in a way a generic "Medicare 101" page never will.

Here's the counterpoint before you think it: the numbers are public, so copying them onto your site isn't original research. True. The original part is the analysis, which no national quote site will write for your county. What has the penetration rate done over the last three Septembers? How many contracts serve the county versus the state average? Each of those is a sentence a local agent can write with authority and a national site cannot. That analysis, next to a sourced figure, is the citable unit. A page you refresh every AEP with a visible "updated" date also gives crawlers a reason to return, which we covered in how often ChatGPT crawls a website.

Does Dataset schema make AI quote you?

Not by itself, and we'd rather say so than sell you markup. Google's Dataset structured data documentation says the markup makes datasets easier to find in its Dataset Search tool. It requires two properties, name and a description of 50 to 5,000 characters, and recommends creator, spatialCoverage, temporalCoverage, variableMeasured, license, and citation. It counts "a table or a CSV file with some data" as a dataset, so a county enrollment table qualifies.

But Google's AI features page says there is "no special schema.org structured data that you need to add" to appear in AI Overviews or AI Mode. The best independent evidence agrees: Ahrefs tracked 1,885 pages that added JSON-LD schema between August 2025 and March 2026 against 4,000 control pages and concluded that "adding schema produced no major uplift in citations on any platform." AI Overviews citations moved about −4.6%, AI Mode +2.4%, and ChatGPT +2.2%, the last two indistinguishable from zero, per their May 2026 study.

So what is Dataset schema for? It declares the county, the time period, and the source in a machine-readable way, it gives Dataset Search a reason to list you, and it costs nothing once your template carries it. We add it to every county page we build. We just don't pretend it's the lever. The lever is the sentence.

How do I write the sentence an assistant can lift?

An AI assistant quotes passages that stand alone. A number without a place, a date, and a source is a claim, not a citable unit. Every statistic should survive being copied into a chat window with nothing around it:

• Place first, then number, then date, then source, in one sentence. "In [County], [State], [X]% of Medicare beneficiaries were enrolled in Medicare Advantage as of [month year], according to CMS's State/County Penetration file." Then link the file.
• One fact per sentence. Four short sentences quote cleanly. One run-on gets paraphrased and loses your attribution.
• Put a visible "Data updated [month year]" line near the figures and match it in the page's dateModified. Undated numbers are worse than no numbers.
• Answer the question in the heading, and link the cms.gov source rather than a news article about it. "How many people in [County] are on Medicare Advantage?" as an H2, followed by the sentence, is the shape that gets lifted. Our post on writing content AI will quote goes deeper.

What are the compliance limits on publishing these numbers?

The numbers are public federal data, and quoting them with a source is ordinary factual content. The risk is in the framing. Rules of thumb, to confirm with your FMO or carrier compliance contact rather than take from a website vendor:

• State, don't steer. "[X]% of beneficiaries in this county are enrolled in Medicare Advantage" is a fact. "Most people here choose Medicare Advantage, so you should too" is a recommendation dressed as a statistic.
• Describe the market, don't rank plans. "Three carriers hold most of the county's MA enrollment" is descriptive. A carrier league table with enrollment counts starts to look like plan promotion.
• Keep the required disclaimers on the page: the TPMO "we do not offer every plan available in your area" language and the non-affiliation disclaimer, as your FMO specifies.
• Never call a $0-premium plan "free," and don't invent precision. If a cell is suppressed or a figure was revised, say so. An assistant that finds your number contradicts CMS will trust CMS.

Done that way, a county data page makes no promises, cites the government, and shows local expertise without a single superlative.

Where this fits in a Found Agents build

County pages carrying these figures, refreshed on a schedule and wrapped in Dataset, FAQ, and Organization schema, are part of the Growth plan. The pattern is in our pillar guide, answer engine optimization for insurance agents. But nothing here requires us. The files are free and the sentence format is above.

Frequently asked questions

How do I find Medicare Advantage enrollment in my county?

Download the MA State/County Penetration file from the CMS Medicare Advantage/Part D Contract and Enrollment Data pages. It is a free monthly file with one row per county showing eligible Medicare beneficiaries, Medicare Advantage enrollees, and the resulting penetration percentage. Filter the spreadsheet to your state and county and the three numbers you need are on one line.

How is Medicare Advantage penetration rate calculated?

Penetration is the number of Medicare Advantage enrollees in a county divided by the number of Medicare-eligible beneficiaries in that county, expressed as a percentage. CMS computes it in the State/County Penetration file, so agents do not need to calculate it themselves. Rates vary widely between counties, which is why county figures are more useful than state or national averages for describing a local market.

How often does CMS update county Medicare enrollment data?

Monthly. CMS says the monthly updates to its Medicare Advantage and Part D contract and enrollment reports are scheduled to be posted by the 15th of each month, and the Medicare Monthly Enrollment dataset on data.cms.gov is also published on a monthly cadence. A county page that cites the month and year of the file it used is easy for a reader or an AI assistant to check.

Does Dataset schema help my website show up in AI answers?

Not on its own. Google documents that Dataset structured data makes a dataset easier to find in its Dataset Search tool, and separately states there is no special schema.org structured data required to appear in AI Overviews or AI Mode. A 2026 study of 1,885 pages that added schema found no major citation uplift on any platform. Dataset markup is cheap and correct to add, but the citable asset is the number itself: a clear sentence with the figure, the county, the date, and a link to the CMS source.

Can I publish CMS enrollment numbers on my insurance agency website?

Yes. CMS enrollment and penetration files are public federal data, and quoting them with the source and date is ordinary factual content. The compliance line is how you frame them: state the numbers as facts, do not present enrollment share as a reason a reader should choose a particular plan type, and keep your required TPMO and non-affiliation disclaimers on any page that discusses Medicare plans. Confirm your framing with your FMO or carrier compliance contact.