Another reason...  

Everyone should do their own taxes. Clearly we don't understand how tax rates work.

Kristina Collins, a chiropractor in McLean, Va., said she and her husband planned to closely monitor the business income from their joint practice to avoid crossing the income threshold for higher taxes outlined by President Obama on earnings above $200,000 for individuals and $250,000 for couples.

Ms. Collins said she felt torn by being near the cutoff line and disappointed that federal tax policy was providing a disincentive to keep expanding a business she founded in 1998.

“If we’re really close and it’s near the end-year, maybe we’ll just close down for a while and go on vacation,” she said. [More]

Plenty of bloggers have jumped on this innumeracy - i.e. the above lady's tax rates would only go up on income OVER $250,000 - but hooting derisively doesn't solve the problem.

You see these idiots every time a tax hike becomes possible again. They have no apparent idea how marginal rates work. Right now, if her and her husband make $250,000, they pay at most a 33% tax on some of that income. If they made $251,000, they would have to pay the same rates for everything except that last $1000 -- that, they'd be taxed at 35%. If the rates increase across the board that top rate becomes 39.6%.

How do people still not understand that, and how does it color the debate over taxes? Barack Obama's managed to win two elections on a pledge to hike that top rate, and yet the people who don't understand it manage to get quoted every year. [More]

Maybe Kevin Drum has a slightly less irritating way to help: do the math for them.

But I agree with all of them that this inability to grasp the arithmetic of income taxes is a real factor in the public debate about how to resolve the upcoming fiscal confrontation.