Shopping for gifts isn’t the only reason so many of us break out our credit cards and checkbooks in December: According to Blackbaud’s Charitable Giving Report, it’s also the most popular time to make a charitable donation. Why? “People are in a giving mindset at this time of year,” says Jacob Harold, president and CEO of GuideStar, a site that gathers information on nonprofits. “And of course, there’s the tax deduction.”

To qualify for a break from Uncle Sam for your 2016 taxes, you must make donations by December 31. If you haven’t given already, that’s a solid reason to consider being charitable before New Year’s Day rolls around. But the organization you pick and the way you give are just as important as your timing. Here, four ways to help your contribution make the greatest possible impact.