As one who had problems with...

As one who had problems with the IRS when I was a grad student in the early '60s, I suggest that the grad students look into possible tax liabilities. The IRS insisted that my TA income was taxable, but I was the only one in my class "picked on." My wife and I took a big hit but survived. Ironically, we got a refund, with interest, a couple of months after I got my Ph.D.