For many people, giving to charity will have minimal effect on their taxes. Non-profits love to attract donations by saying the money is tax deductible, but for most people, it doesn't work out that way. You will only itemize deductions if they exceed your standard deduction.
The IRS allows you to either "itemize" your deductions (where you list each deduction you can take) or take the "standard deduction". Consider a married couple filing jointly in 2011. Their standard deduction is $11,400. They are in the 28% tax bracket.
They donate $100 of old clothes to the Goodwill, and are looking forward to deducting that on your taxes, and getting $28 of that back. If that's their only deduction, though, they'd have to give up the standard deduction to take the itemized deduction. Not worth it.
Suppose instead they have $11,500 of deductions in 2011. Now we're talking, right? No. The tax impact of itemizing is only $28, since they only exceeded the standard deduction by $100. The cost of having a tax accountant fill out the itemization form probably offsets that small gain. There's also all the time that went in to tracking those deductions over the year. Not worth it.
Tax deductions only become worthwhile when they significantly exceed the standard deduction. You need some big ticket items to get past the itemized deduction threshold. For most people, this only happens when they have a mortgage, as the interest on a residence is deductible.
Folks love to suggest that having a mortgage is a good deal, because the interest is deductible. However, since you have to exceed the standard deduction before it makes sense to itemize, it's not likely to be a big win.
For most people:
- if you don't have a mortgage, you'll never itemize deductions.
- if you have a mortgage, you can deduct your donations, but don't count on getting your interest back.
TL;DR: Give to charity because you want that charity to have your money. Tax implications are minimal; let your accountant sort it out.
Disclaimer: I am not an accountant.