Avoiding the most dangerous risks of climate change requires increased policy ambition around the world, including strong federal-level action in the United States. Economists have long pointed to a carbon tax as an important part of any cost-effective portfolio of climate policies. A carbon tax would reduce emissions by raising the costs of carbon-intensive products, thus causing producers and consumers to factor the costs of climate change into their market decisions. The purpose of this commentary is to describe the major design decisions associated with a federal carbon tax, particularly carbon tax rates, revenue use, and regulatory changes. The authors analyze their implications on US energy markets, emissions, and the economy. They focus on two carbon tax scenarios that resemble federal legislation proposed in 2018, one by Democratic members of Congress led by Sheldon Whitehouse and one by Republican Congressmen led by Carlos Curbelo.