@shyparentalunit - The part of a PhD stipend that is “salary” and expected to go for living expenses is taxable. If your kid hasn’t changed state of residence, that can make a difference at least in the state income taxes. I know one not-smart-about-regular-life brand new PhD who retained residence in her home state all through her grad program despite having moved to a no-state-income-tax state for her PhD program. 