Estimating share of workers with employer/union sponsored health insurance coverage

I am trying to calculate what share of workers have access to employer/union sponsored health insurance coverage using the HINSEMP variable from ACS 2017-2021. Is there anyway to restrict the sample to policy holders (so filtering out individuals that have coverage through their families or spouses)? If no, are there other variables that can produce a similar calculation at the county level?

Thank you!

There is no information in the ACS that explicitly or implicitly identifies the insurance policyholder within a health insurance unit (HIU). You might consider the number of people in the HIU (i.e., single-person HIUs should be easy to identify), employment status in conjunction with the variable HINSEMP for HIU members (i.e., who is eligible to be the policy holder if the HIU has employer-based coverage), and the age of individuals in the HIU (i.e., are children or adults more likely to be the policy holder) to infer probable policy holders. I would highly recommend reading over this page on health insurance variables in the ACS, especially the section on edits in IPUMS-USA. This paper describes in more detail the editing of ACS health insurance coverage variables.