how does an employer get notified that an employee is receiving social security medical coverage?

Hi,

I'm not sure I understand the crux of your question. Your employer wouldn't necessarily be notified if you have Medicare coverage, but if you have health insurance through an employer and you're also signed up for Medicare, the insurance companies involved would need to know about the other coverage in order to coordinate payment of any claims. In that event, you would most likely need to notify the appropriate insurance companies yourself.

Best, Jerry