Schools and departments can NEVER pay an employee through Accounting (i.e. check request or NPO). Employees must be paid through Payroll (i.e. True Time or Time Sheet). Accounting only pays vendors (businesses) and reimburses employees for purchases they made on behalf of the District.
If an employee has a business which:
a) has a business license, and
b) does work for other entities beside the District, and
c) completes an "Independent Contractor Declaration," and
d) the work they are doing has no similarity to the work the District hired the individual to do, then that business may be paid through Accounting.
However, this is extremely rare and care should be taken to ensure the above four items are true. When you have any doubt about a certain situation, it is safer to pay the person through Payroll as an employee.