I am a PhD student and work as a Teaching Assistant for a university in NY. Last year I was invited to present at a symposium. This symposium was held in TX, but was organized by a university in CA. I paid for my travel expenses (symposium registration, plane tickets, uber, food and lodging) out of pocket, but the organizing university later reimbursed me.
All the reimbursment corresponded to actual expenditures and I provided the organizing university with copies of the receipts (I still have the originals). They didn't witheld any taxes nor generated a tax form for me.
So, my question is: should I consider this reimbursment as income and pay taxes for it? And in case the answer is yes, how should I report it provided that I didn't receive a tax form for it?
No, this isn't income. It's an expense reimbursement.
If they had provided you with a tax form then you would report it and also report the expenses so that it was a net-zero transaction. But since it has not been reported to the IRS all of that is unnecessary. Just leave it off.