My parents use my credit card for everyday purchases and then pay me back for those purchases because it helps me earn cash back. As a result, they deposit money into my bank account every month that is equal to what they spent. They are the only ones who use that credit card. Is that money they deposit into my account taxable? I've read on money given as gifts is if it's over $14,000 USD, but my situation is a little unique. They do not claim me on their taxes nor pay for anything. I am completely independent, they only use my credit card and pay me back for what they spent (rounded to the nearest dollar).
You are giving your parents a short term loan. The value of that loan is likely far less than the gift tax exclusion for the year. You only need to account for the money you loaned to them and the money they paid back. This is not income for you unless they pay interest. It is not a gift from them because they are just paying you back.