You sure about that ?
I'm not from the States, but I do know a bit about Accounting and Finance, and there are a ton of businesses that make $250,000 gross ... that's not that much money (much less than a $1,000 per day in revenue), and when you subtract the expenses, most of those businesses with $250K gross wouldn't have all that much profit left over.
So not knowing a single thing about the components of Obama's tax plan, my blind guess (and the logical thing) would be that it would be based on $250,000 net.