Update: On December 20, 2017 the House approved the GOP's overhaul to the nation’s tax code. A provision in the plan had originally proposed taxing graduate students’ tuition waivers. But in the final version of the combined House-Senate tax bill, which now makes its way to President Trump to be signed into law, tuition waivers will remain tax-free.

Amanda Coston was preparing for a meeting with her advisor Monday afternoon when her friend, another first-year PhD student in Carnegie Mellon's machine learning department, knocked on her door. Had she seen the email? A few minutes earlier, the university's Graduate Student Assembly had sent a Google Doc to department representatives across the university, and those reps had forwarded the document to their grad students.

That document, which you can see for yourself here, details the devastating impact the GOP's recently unveiled tax-reform plan could have on the university's PhD candidates. Buried in that plan is a proposed repeal that would cause graduate students' tuition waivers to be counted as income—making them subject to taxes. The document analyzes how the repeal would affect graduate students in colleges across Carnegie Mellon.

It's pretty bleak.

The annual stipend for a PhD student in Carnegie Mellon's school of computer science is about $32,400. The university covers the student's $43,000 tuition, in exchange for the research she conducts and the courses she teaches. Under current law, the government taxes only a student’s stipend; the waived tuition is not taken into account. But under the GOP bill, her annual taxable income would rise from $32,400 to $76,234. Even factoring in new deductions also included in the proposal, the CMU document estimates her taxes would amount to $10,209 per year—nearly four times the amount under current law. That would slash her net annual stipend by 25 percent, from $29,566 to $22,191.

"It was just such a shock," says Coston, who expects her degree will take another five years to complete. If the repeal were to become law, it would take effect in 2018–2019. "It really changes the calculus on my finances. This suddenly makes a lot of things like rent, car payments, groceries, all that stuff, no longer affordable."

And not just for her. Current and would-be graduate students fear that, were the bill to pass, getting a PhD in the US could become financially impossible. "I monitor all legislation at the state and federal levels that could affect graduate and professional students, and this is just—this would have the greatest negative impact of anything I've seen," says Samantha Hernandez, legislative director of the National Association of Graduate-Professional Students. "It would be devastating."

For years, PhD candidates have "paid" for their educations almost exclusively through research and teaching—working in labs, TAing courses, hosting office hours. It works like an apprenticeship: Trade five years of your life learning and working in a field that interests you in exchange for a meager, but livable, salary. "The point is to be stressed about class work and research—not finances," Coston says. Fewer than 10 percent of PhD candidates in STEM fields rely primarily on their own money to pay for grad school; and in 2015, more than three-quarters graduated with no debt. (At least from their graduate programs; plenty of graduate students complete their PhDs burdened with debt from their undergrad years.)

But removing the promise of a living wage would dramatically affect people's ability to pursue a graduate degree. "I think we'd see a shift in who even starts such a program," says UT Austin computational biologist Claus Wilke, who also blogs on the subject of professional development in academia. A graduate education would quickly become something you pursue only if you can pay for it.