The GOP unveiled a final tax plan on Dec. 15 with new cuts for the rich and an expanded credit for working families. The plan, which Republicans appear to have the votes to pass through the House and Senate, would amount to the largest overhaul of the U.S. tax code in more than 30 years. The backbone of the plan is the largest-ever one-time reduction in the corporate tax rate, dropping it from 35 percent to 21 percent starting in 2018. The final GOP tax bill is complete. Here’s what is in it.