Paying rent with a roommate question.

My current roommate does not have a bank account. She is a server that has her tips paid to her via a check just like a regular job. Her wages are taxed. Usually she will give me cash or a check made out to her that will be signed over to me to pay rent and I will deposit it into my bank account and pay rent that same day through the website Cozy.

Today I was told that those cash deposits and checks would be taxed as income on my behalf. Meaning I would have to pay taxes on another $9000 over the course of the year.

I need to know if this is correct or if what I was told was wrong. Thank you all so much for your help. For reference I live in Tennessee in the United States.