Colorado offers an income tax credit to Colorado resident individuals and C corporations for the preservation and rehabilitation of a qualified historic property. The structure must be at least 50 years old, and must be:
a) designated individually or as a contributing property in the State Register of Historic Places;
b) designated as a landmark by a certified local government; or
c) designated as a contributing property in a designated historic district of a certified local government. If the property on which a taxpayer wants to claim this credit has none of these designations, the taxpayer must apply for and secure such a designation. [§39-22-514, C.R.S.]
https://www.colorado.gov/pacific/sites/default/files/Income1.pdf