can I write off cash to charity?

Answer 1

1) Charitable contributions are an itemized deduction. Chances are that, if you do not own a house and pay a mortgage, you will not have enough to itemize.

2) As of 1/1/07, even if you do have enough to itemize, you need a receipt for the deduction. For amounts under $250, a cancelled check counts as a receipt. For amounts over $250, you need a receipt from the charity. If you gave cash and didn't get a receipt, sorry, no deduction.

Answer 2

I depends on the charity.
Usually they give you a tax receipt if it's deductible.