"Here’s the Obama plan in brief. The Bush tax cuts would be extended for households with an annual income under $250,000 (or $200,000 for individuals), but the tax cuts would expire on any income above $250,000. That means, for example, if you make $300,000, your tax rate would rise a few percentage points, to the Clinton-era rates, but only on the portion above $250,000; in this case, only on $50,000. Bottom line: no one—not a billionaire, not someone making $251,000—would have to pay more taxes on that first $250,000.
There’s a widespread misconception, however, and it’s causing a lot of unnecessary fear. It’s the faulty belief that if your income is above $250,000, you’d have to pay the higher rates on all your income, as if you were suddenly being moved entirely into a higher tax bracket. That is wrong."