From “Andrew Cuomo: Healthcare workers who volunteered to help New York with pandemic must pay state income taxes“, 6 May 2020, Washington Examiner:
Healthcare workers who traveled to New York to help patients during the coronavirus pandemic may not have realized they were also going to be assisting the state dig itself out of a financial hole. […] “Ken Isaacs, the vice president of Samaritan’s Purse, a nonprofit organization that set up a temporary hospital in Central Park to help with the pandemic, told PIX 11 he was shocked to learn that workers who volunteered to come to the state would have to pay the state’s income tax.”
Thus, a nurse from Texas (which has no state income taxes), who volunteers to work in New York, will have to file paperwork, and pay taxes for money she is paid in Texas.