The underlying data used on this website includes the CMS
Contract / Plan / State / County data set. This data was selected
as it provides the most granular level of enrollment information.
However, it comes with the following tradeoff:
Due to HIPAA privacy laws, CMS will not publish enrollment
counts when the value is 10 or less. E.G. if plan X in county Y has 10 enrollees,
the data will show 0. But if there are 11 enrollees, the data will show 11.
Because of this, the total enrollment number shown on this site
will be lower than the total enrollment number published by CMS's
summary report. Historically, this difference has been around 1%.
CMS has reported:
There was an issue with MARx processing and not all of the enrollment for 1/2023
and 2/2023 is reflected when there was a crosswalk exception.
It is our understanding that this has caused the AEP 2023 enrollment
numbers to be understated and the OEP 2023 numbers to be overstated
as the missing AEP enrollment information was corrected in OEP.