There are some great big, honking, ugly, nasty problems with this proposal.
The one problem I want to focus on here is one that, for some reason, hasn't been in the news. It's the elimination of the itemized deduction for medical expenses.
Look, I know that for a lot of people this is no big deal because they weren't getting much benefit from the deduction anyway but there is a class of person who will be absolutely hammered by this change. People in assisted living and nursing homes will be creamed.
Let's say that Grandma has Dementia and needs to be in an assisted living facility. The facility costs $6k/mo ($72k/yr). She has SS income of $20k/yr and a survivor's benefit from her husband's pension of $20k/yr. The rest of the money she has is in an IRA her husband left her and, because he was good about saving, there's $500k available. If she was at home she'd be able to live on the $40k without any problem but because the needs the assisted living she's now $32k short and that has to come out of the IRA.
Under current tax law she'd be able to deduct most, if not all, of her assisted living expenditure. This would reduce her taxable income (including the $32k from the IRA) to zero.
Under the proposed legislation she'd have an AGI of $69k (15% of her SS would not be treated as taxable income) and a Standard Deduction of $12k giving her taxable income of $57k. $45k would be taxed at 12% and $12k would be taxed at 25%. Her tax hit would be $8,400. Where is the money to pay her tax going to come from? Her IRA, of course. That means she'll have to pull roughly $42k/yr from the IRA to make up for the tax and still have $32k to pay for the assisted living. Basically, Grandma gets whacked with a $10k tax hit because of this change and, since she's already got everything in the IRA, she can't make a change to mitigate the beating she's going to take.
Keep this in mind too, in this example Grandma has $500k in the IRA. The result will be the same if she only has $150k in there. That makes a difference of being able to support 5 years of assisted living or just 3.5 years.
There is no way aging taxpayers who have the bulk of their savings in qualified plans can escape a trap like this.
I know that right now this is just a proposal but if this stuff goes through we're going to have a whole lot of very screwed people. But who knows, maybe they'll all be happy because it will be a tiny bit easier to do their taxes.