Why is this in the tax bill? Congress has complex rules around passing permanent tax cuts that raise the deficit. The GOP is attempting to present a tax plan th

Why is this in the tax bill? Congress has complex rules around passing permanent tax cuts that raise the deficit. The GOP is attempting to present a tax plan that has very large tax cuts and an equal amount of new revenue (e.g., less deductions, less exemptions). The complex rules around deficit-neutral bills don't make provisions for future changes in behavior negating a passed bill. So Congress would like to take away this exemption to help pass their current bill; universities will change their behavior to keep the profitable graduate system in place.