This question specifically involves FAA regulations in the U.S.
Some U.S. corporate flight departments will set up a separate business entity for their flight operations to limit the liability of the parent company. Because this business operates with on-demand passenger transport for compensation as its primary business, it must be operated as a part 135 (or 125 if they are running big ships) instead of part 91. In some cases, this new subsidiary will provide additional revenue stream by servicing outside clientele in addition to meeting the travel needs of its parent company, and sometimes they remain exclusive.
If a corporate flight department doesn’t want to use their aircraft to supplement income with charter flights, is liability the only reason to set up and operate as a Part 135 instead of keeping it Part 91?
Are there any other reasons, aside from liability and supplemental income, to bother with a 135?