One-half of the outstanding principal amount of loans guaranteed by the corporation and owned by a lender as of January 1 each year shall be deductible from the assets of the lender when determining the value of shares of the lender, or when determining the net worth of the lender, for purposes of any ad valorem taxation imposed on the lender by the state or by any political subdivision of the state. All income earned by a lender on loans guaranteed by the corporation shall be exempt and free from any type of income tax imposed on the lender by the state or by any political subdivision of the state. It shall be the duty of all revenue and tax officials of the state and of political subdivisions of the state to enforce and give full force and effect to this Code section and to the intent, hereby expressed, of the General Assembly better to assure through this means the accessibility of educational loan funds to local citizens and persons from local lending institutions.