Until tax season comes around, Mary Ritchie and Kathy Bush can act like any legally married couple raising two boys. In midwinter, that means watching lots of basketball. "We go to every game and every practice," Bush said. But when they file their tax return with the federal government, they are no longer married. The return is supposed to be "true, correct and complete" by law, but they cannot check "married, filing jointly." The loss of this routine tax break costs them as much as $6,000 a year.