Paycheck

Hey, sorry if this sounds dumb. I work two jobs, one in retail and then one as an hostess. For some background information, My hostess job doesn’t do direct deposit so she gives me a check. She wanted me to buy her some shoes from my retail using my discount from my own account using money from my bank. I paid it with my own money and she later gave it back to me.. but the thing is she paid me back on my paycheck. Instead of giving me cash or like her personal check, she gave me the 300$ through a work check, I earned 600 that I worked, and then she added 300$ total around 900$ to my paycheck. I heard from others that the tax deductible is a lot. I didn’t work the 300$ i used my own bank to pay for it, is this wrong?