Here's why this is so important. Ryan's proposed tax cuts are above and beyond the Bush tax cuts, which he wants to make permanent. According to the Tax Policy Center, this means that Ryan's plan would cost an additional $400 billion in revenue in 2015. So to stay revenue neutral, he needs to eliminate deductions and tax credits worth about $400 billion. The technical name for all these deductions and credits is "tax expenditures," and the table below, compiled from a recent report of the Joint Committee on Taxation, shows their estimates for the total value of tax expenditures in 2015:
Do you see how hard this is? The big ticket items are things like taxing healthcare and pension benefits; the mortgage interest deduction; the Earned Income Tax Credit; the charitable contribution deduction; various state tax deductions; and exclusions for Medicare and Social Security benefits. Needless to say, those are going to be eliminated over a whole bunch of dead bodies. Other big ticket items include tax breaks on dividends, capital gains, inheritances, and offshore income, and all of those would be eliminated only over Paul Ryan's dead body. There's not a single thing in this entire table that wouldn't be a stupendous political lift, and the prospect of eliminating not just one of them, but $400 billion worth of them, is very slim indeed.
So yes, unless Paul Ryan's plan is to tax 401(k) plans, the mortgage deduction and employee health care plans, he's basically lying. Of course, there's a pretty good chance that this is his plan all along, getting rid of all that and the Earned Income Tax Credit while saying that "too many Americans don't pay income tax".
And remember, Mitt Romney is 100% behind the Ryan Plan.