The Patient Protection and Affordable Care Act includes a 40% excise tax on high-cost employer-sponsored health coverage. Called the Cadillac Tax, it was to be implemented beginning in 2018, but the Consolidated Appropriations Act of 2016 (P.L. 114-113) delays implementation until 2020. A report from the Congressional Research Service (CRS) provides an overview of how the excise tax is to be implemented.
The report can be accessed at https://www.fas.org/sgp/crs/misc/R44147.pdf.