The government entity that owns the building determines the allocation, provided that the designer creates the required technical specifications to be eligible.
If there’s only one designer, the process is simple. However, in the case of most construction projects, there are multiple parties who qualify as designers, making the allocation decision less straightforward. For these types of projects, the government entity may allocate among several designers or choose to allocate the entire project to the primary designer.
Some government entities have created processes for selecting a designer for the Section 179D allocation and many involve finding the government representative who’s most familiar with the project to help determine who should get the allocated deduction.