For U.S. tax deductible charitable donations (501(c)(3)), it is mandatory to have in your hands, before the earlier of filing your tax return or the original fi

For U.S. tax deductible charitable donations (501(c)(3)), it is mandatory to have in your hands, before the earlier of filing your tax return or the original filing deadline, a written acknowledgement of your donation from the donee including amount, date, and a statement that you received nothing of value in return. If not, it is not tax deductible.