Currently, when graduate students work as teaching assistants, the university waives their tuition and pays them a stipend. Under current tax law, students pay income tax “only” on their stipend. A provision in the tax bill currently under consideration would count the waived tuition as income, on which the student would have to pay taxes as well.
A calculation by a Berkeley physics graduate student (source) finds that a student who work as TA for both semesters and the summer, is payed at “step 1” of the UC Berkeley salary scale, and is a California resident, currently pays $2,229 in federal income tax, which would become $3,641 under the proposed tax plan, a 61% increase. The situation for EECS students is a bit different: they are paid at a higher scale, which puts them in a higher bracket, and they are often on a F1 visa, which means that they pay the much-higher non-resident tuition, so they would be a lot worse off (on the other hand, they usually TA at most one semester per year). The same calculation for MIT students shows a 240% tax increase. A different calculation (sorry, no link available) shows a 144% increase for a Berkeley EECS student on a F! visa.
This is one of the tax increases that go to fund the abolition of the estate tax for estates worth more than $10.9 million, a reduction in corporate tax rates, a reduction in high-income tax rates, and other benefits for multi-millionaires.
If you are a US Citizen, and if you think that graduate students should not pay for the estate tax of eight-figure estates, you should let you representative know. Usually calling, and asking to speak with the staffer responsible for tax policy, is much better than emailing or sending a physical mail. You can find the phone numbers of your representatives here.
If you have any pull in ACM, this is the kind of matter on which they might want to make a factual statement about the consequences for US computer science education, as they did at the time of the travel ban.