How does SBA define the term "principal office?"

It’s the location where the greatest number of employees at any one location actually perform their work, except for construction and service industries, which have exemptions based on their occasional need to assign employees at the contract location. Notice that the ?principal office’s definition can mean something very different from a company’s headquarters. It could happen that a small business might have a headquarters in a non-HUBZone location and establish a principal office within a HUBZone locality and still qualify legitimately for program participation.(more details – see ‘Regulatory Amendments’ that follows).