It is tempting for people who earn less than $400,000 to think that they got off easy this week under the tax deal to end the fiscal impasse, given that only those with incomes above that level will be in a higher income tax bracket in 2013. But the legislation that both houses of Congress have now approved could increase taxes on people with incomes that are not quite that high as well. That’s because the bill includes language that begins to do what both President Obama and Mitt Romney proposed at various points in the past: Limit certain tax...