Every organization, otherwise exempt under section 43-1201 but having unrelated business taxable income, shall:
1. File a return, verified by an executive officer under penalties of perjury in the form prescribed by the department on or before the fifteenth day of the fifth month after the close of the taxable year, reporting its income from such activities.
2. Pay a tax at the rates prescribed in section 43-1111 on its unrelated business taxable income as defined in section 43-1231.