Simplifying Management, Access, Reallocation, and Transfer of Spectrum Act or the SMART Spectrum Act This bill requires the National Telecommunications and Information Administration to implement an incumbent informing capability in its regulation of the electromagnetic spectrum. The bill also outlines minimum requirements for the capability that address protection of classified information and other matters. Incumbent informing capability is a mechanism that facilitates the sharing of spectrum allocated for both federal and nonfederal uses; it enables federal users to reliably inform nonfederal users when and where the federal systems are operating in order to manage harmful interference between the federal and nonfederal uses.