National Park Service
Does it surprise you that the National Park Service (NPS) is the first stop in your quest for historic property tax breaks? In fact, the NPS partners with the IRS to administer the Federal Historic Preservation Tax Incentives Program. Their certification application for a listing in the National Register of Historic Places (NRHP) is the golden ticket to tax breaks and the best way to designate your property as a historic site [source: National Park Service]. Note that to get federal tax breaks, not only must you get your property listed on the NRHP, but you must also provide specific plans for renovation to the site. It's these renovations that you'll get a break on.
If you're thinking about buying into an existing historic property, perhaps with the thought of further renovations, check the NRHP to make sure it's already registered (or consider making successful registry a contingency of sale) [source: National Park Service].