Back when I was a lowly intern on the Hill in the 90’s and flat tax proposals were enjoying their second(?) renaissance, I got talking about them to my boss (a conservative Democrat) on a car ride and he said something that always stuck with me. I don’t think it gets more succinctly correct than this:

There’s a simple reason that no flat tax will ever pass, nor should one. First, no matter how you structure it, the richest people will pay less than they do now. That’s a basic consequence of getting off a graduated tax. Any sane plan is going to also have an exemption for the first 20 or 25k of income, to help the poor. So if the tax is good for the rich and good for the poor and still revenue neutral, who does it screw? The middle class.

Second, everyone keeps saying how simple it is, that you can do your taxes on a post card. Nonsense. Simplicity is not inherent to the flat tax any more than it is to the graduated income tax. We could eliminate all deductions and adjustments from the current income tax, and you could do the three-bracket math on a post card too. But more importantly, there’s zero chance a flat tax doesn’t eventually get loaded up with deductions and credits.

All that said, it takes some real effort to come up with a flat tax as bad as the one Rick Perry is now proposing, which would allow people to chose between their current taxes and a 20% flat tax. Everyone from Jon Bernstein to Kevin Drum to Reihan Salam have already eviscerated it this morning, so I won’t go into detail, but here are three quick thoughts:

1. Under Perry’s plan, we wouldn’t get any benefit of reforming the zany current system. Perry’s plan is doomed for a lot of reasons, but this is my favorite. The tax system is completely broken in this country, so we’re going to reform it by letting some people pay less in a really simple way, but some people stick with the old system. So in order to do your taxes in the simple way, you’ll have to do them in the hard way to see if the simple way is better. Awesome. It’s  not even good politics, because it doesn’t let Perry effectively talk about “abolishing the IRS” or “simplifying the tax code.” In effect, we have to keep the entire structure of the current system in place, and dump a new one on top of it. Brilliant. (Sidebar: I wonder how much extra I would pay to do the flat tax and not have to keep any records or do a 1040. I wonder what the aggregate average would be for that question.)

2. I’m pretty sure the only relevant distinction is between zero and one deduction. Every scholarly history of the income tax I’ve seen says the same thing: it started out pretty clean, but over time the carve-outs, deductions, breaks, and all the rest just keep getting piled on. Perry’s plan has mortgage deductions and charitable giving deductions. You think more isn’t coming down the road? You are naive. Once you allow and deductions or breaks or whatever, the flood gates will eventually (and probably pretty soon) open. People love deductions. Makes them feel like they are getting something that others aren’t. My mom — who is a pretty smart lady — once told me that she’d rather keep her mortgage deduction than pay overall less taxes. I could not change her mind. That tells you all you need to know. If you can’t abide by an absolutely no deductions policy, you are probably headed toward the full menu.

3. Why not a graduated income tax that is as simple as a flat tax? If someone proposed this, it might actually get me thinking. Just like my old boss said. Three or four brackets, no deductions or credits. Use the postcard. Make it as progressive as you want. I guarantee this polls better than any flat tax ever has. Still a pipe dream, but now at least it’s a normatively desirable pipe dream.