But the tax math will be tricky for many high-earners in states with the highest tax rates. The bill reduces the top federal tax rate to 37% from 39.6% and increases the threshold at which it kicks in to $600,000 from $470,000 for couples filing jointly. Our friend Don Luskin did the math and says that high earners in states with top rates exceeding 6.56% could see their tax bills increase.