Conn. Gen. Stat. § 14-28: Passenger motor vehicle plates for livery cars or taxicabs.

For a fee of seven dollars, the commissioner may furnish to each holder of a livery or taxicab registration an additional passenger motor vehicle number plate or set of number plates in accordance with the provisions of subsection (a) of section 14-21b to be used on the motor vehicle in livery service or taxicab when not engaged in public service business, provided such vehicle or taxicab meets the criteria for registration as a passenger vehicle under the provisions of this chapter.