Charitable donations a deducted from your taxable income. The impact to the amount of tax you pay depends on your tax bracket. So if you are in a 25% tax bracket you will save $.25 per dollar you donate to charity. There are limits to the amount of charitable donations you can claim depending on your filing status (single, married, etc.) and your taxable income.

In order to claim charitable donations you have to itemize your deductions which means that you can't use the 1040EZ form. Depending on your situation it may be better to take the standard deduction rather than itemize.

The charitable organization will issue you a receipt for donations given during the tax year and you should receive that from them by the end of January. I believe you need to have a receipt in order to legally deduct the donation from your taxes.