In coordination with states, the U.S. Environmental Protection Agency (EPA) faces a number of policy challenges as it develops its guidelines for carbon pollution standards for existing power plants. These range from over-arching issues that will impact the foundation of the standard, such as whether it will come in the form of an emissions rate or a mass-based carbon budget for each state, to narrower questions such as how to account for offsets in an existing state greenhouse gas program.

This brief seeks to establish a common understanding of these intertwined challenges to help EPA, states, and other stakeholders see how these issues interact and where the solution to one may complicate another.