What happens is when you have two incomes in a family, they are thrown into a higher tax bracket than they would be if they were separated, if they were divorced or if they were just living together. What happens to women is that they will come in and out of the work force. They often start out working and leave to raise a family. When they return, either part time to full time, those extra dollars the family receives from that is taxed at the higher level. The cumulative effect is that her earnings are taxed at the 40 to 50 percent marginal tax rate.
Women are the ones generally who take the time to raise the family.
In most cases, it's women who are making those choices. It's a direct tax on women who want to have careers and be married. The work that was done on that by a Yale Law School professor points this effect out. By standing still, we're falling behind as we enter the new economy of the 21st Century. Our children 44th on SAT scores in education, and half of our children don't pass basic 9th grade math and English in high school examination.