The Authority shall not be required to pay any taxes or assessments of any kind whatsoever and its bonds, their transfer, the interest payable on them, and any income derived from them shall be exempt at the time of issuance and at all times from every kind and nature of taxation by this State or by any of its political subdivisions, municipal corporations, or public agencies of any kind, except for estate, transfer, and inheritance taxes as provided in Section 12.
     For purposes of Section 250 of the Illinois Income Tax Act, the exemption of the income from bonds issued by the Authority shall terminate after all of the bonds have been paid. The amount of such income that shall be added and then subtracted on the Illinois income tax return of a taxpayer, under Section 203 of the Illinois Income Tax Act, from federal adjusted gross income or federal taxable income in computing Illinois base income shall be the interest net of any bond premium amortization.