Interesting proposal, but it’s not clear to me why anyone who makes a contract to pay back a loan should get 20% off if he/she is paying taxes, presumably because they have a job.
I obtained two MAs and taught at the University of Houston
after retirement from self-employment.
My observation on the educational system is that there are simply too many students that are encouraged to go into debt for majors that have no value in the regular job market and there are too few jobs in academia to support them and pay off the loans.
It isn’t good policy to encourage debt by any tax policy that rewards bad outcomes.