The Patient Protection and Affordable Care Act of 2010, which set federal minimums for employer health coverage, including the employer mandate and minimum essential coverage standards.
The SIMERP does not replace, supplement, or otherwise interact with ACA minimum essential coverage. Employees on the program must already have qualifying group health coverage that satisfies their ACA obligation - the SIMERP sits alongside.
Definitions only do so much. A live walkthrough of how all of this connects in your business takes about half an hour.