You are preparing your taxes. All of your documents are in order. You grab you year-end charitable contribution documents and include them as well.
Are all of your donations tax-deductible?
“Of course, I’ve been giving to such and such organization for years.” Unfortunately, this does not guarantee they are (or ever were) a 501(c)3 nonprofit. You should check. If you need help navigating Select Check, I give instructions in #3 here.
Of course you should always check any new organization you are giving to. Be aware that various scams exist. The IRS lays out a few of these scams in Fake Charities Among the IRS “Dirty Dozen” List of Tax Scams for 2015.