Secretary of Interior Standards Calculator

The Secretary of the Interior's Standards for Rehabilitation, codified at 36 C.F.R. Part 67 and administered by the National Park Service, are the ten benchmarks the NPS and state historic preservation offices use to judge whether rehabilitation work respects a building's historic character — and passing them is a prerequisite for the 20% federal Historic Tax Credit. This calculator scores each standard on a 0-10 scale (compatible new use, retaining historic character, treating the building as a physical record of its era, preserving features that have gained their own significance, and preserving distinctive materials and craftsmanship as the first five; Standards 6 through 10, covering repair versus replacement, chemical/physical treatments, new additions, and archaeological resources, are combined into a single averaged input to keep the form manageable) and averages all ten into one overall compliance score.

That average is also expressed as a percentage of the maximum possible 10, and it drives two threshold-based flags: an average of 6 or higher is treated as likely to pass NPS/SHPO review, while 7 or higher is treated as likely to also clear the higher bar for HTC eligibility — both are simplified proxies for a real reviewer's judgment call, not a legal determination. The calculator also surfaces your single lowest-scoring standard, since in practice one seriously deficient area (say, replacing character-defining windows) can sink an otherwise strong application even when the average looks fine. Because Standards 6-10 are lumped into one averaged number here, a project with one very weak standard buried in that group (for example, an incompatible new addition) could look better on paper than it will look to an actual reviewer — for a real submission, score each standard individually and consult your SHPO before finalizing plans.