Do I need to file tax if I lend someone money?

I want to help my sibling by lending her up to $100k to buy her first house. I will not collect any interest from this amount of money, and I will not be the co-owner of this house with her. A bank teller advised me that I can write a statement declaring that I will not be earning or collecting any interest money from the amount of money I lent my sister, and have it notarized to avoid tax problem with IRS and will not need to pay taxes for this amount of money. Is that true? If not, what can I do? I really appreciate your opinions. Thank you!