Starting in 2007, if you claim an itemized charitable deduction of less than $250, you must have a written acknowledgment, cancelled check, credit card statement or other documentation that clearly shows the date and amount of the contribution and the charity’s name. Before 2007, taxpayers could use "other reliable written records," such as a hand-written log, to substantiate donations of less than $250.

For donations of more than $250, you must have an acknowledgement from the charity including its name, the amount and date of the gift and a statement that you did not receive any goods or services in exchange for the gift. Cancelled checks alone will not substantiate a donation over $250.

You don’t have to file any documentation with your tax return, but you will need it if you get audited.