After January 1, 1975, 100 per centum of all vending machine income from vending machines on Federal property which are in direct competition with a blind vending facility shall accrue as specified in subsection (a) of this section. “Direct competition” as used in this section means the existence of any vending machines or facilities operated on the same premises as a blind vending facility except that vending machines or facilities operated in areas serving employees the majority of whom normally do not have direct access to the blind vending facility shall not be considered in direct competition with the blind vending facility. After January 1, 1975, 50 per centum of all vending machine income from vending machines on Federal property which are not in direct competition with a blind vending facility shall accrue as specified in subsection (a) of this section, except that with respect to Federal property at which at least 50 per centum of the total hours worked on the premises occurs during periods other than normal working hours, 30 per centum of such income shall so accrue.

The head of each department, agency, and instrumentality of the United States shall insure compliance with this section with respect to buildings, installations, and facilities under his control, and shall be responsible for collection of, and accounting for, such vending machine income.