Lawmakers have spared graduate students from having to start paying income tax on their tuition waivers.

Graduate students across the country have loudly protested a controversial provision of the tax plans that moved through the House and Senate in recent weeks. The proposal would have significantly driven up the tax burdens for those who receive tuition waivers from their schools. They are often teaching and research assistants.

But the final congressional tax plan, which lawmakers are set to vote on next week, omitted the proposal.

An estimated 145,000 graduate students didn't have to pay for tuition in 2012, the latest year data is available.

Roughly one-quarter of students pursuing doctoral degrees received a tuition waiver that year, according to the Council of Graduate Schools. Some master's degree students receive waivers, too.

Currently, the award is not taxed, but an earlier version of the House plan would have taxed the amount of tuition as income.

The change would have been significant for Benjamin Shih, a Ph.D. engineering student at the University of California in San Diego. He expected to owe an additional $3,600 to the IRS if his tuition was taxed.

The proposal was also criticized by colleges and universities that were concerned it would hurt research programs by making it harder for students to pursue higher degrees. More than half of students receiving a tuition waiver are studying science, technology, engineering or math.

But support for the proposal appeared shaky last week when 31 house Republicans -- who had all voted for an earlier version of the bill that included the provision -- asked party leaders to ultimately leave it out.