In evaluating the impact of Republican candidates' tax plans, Tax Policy Center has been an invaluable resource. After having scored Newt Gingrich's and Rick Perry's plans for revenue and distributional impact, they have done the same for Mitt Romney. The results are also similar, showing revenue losses even when compared against a baseline that extends the 2001/2003 tax cuts.
Romney makes a number of changes to the tax code, but they are not as structural in nature as Gingrich's and Perry's flat tax proposals or Herman Cain's 9-9-9 plan. For starters, Romney extends the 2001/2003 tax cuts, although he excludes the 2009 tax credit expansions that were part of the 2010 extension.
On the individual side, he indexes the AMT for inflation, repeals the tax increases contained in the Affordable Care Act, eliminates the estate tax, and eliminates taxes on investment income for people making less than $200,000. On the corporate side, he cuts the corporate tax rate to 25 percent, permanently extends the R&D tax credit, temporarily extends expensing of capital expenditures, and switches to a territorial system of foreign taxation.
According to TPC, the tax plan reduces revenue by $600 billion compared to current law and $180 billion compared to current policy in 2015 alone. While these numbers are eye-popping, they are actually much smaller than the numbers TPC estimated for Gingrich and Perry. Still, Romney would need significant spending cuts to offset the revenue loss and even more to bring the debt down to a reasonable level.