Section 39-66 - Federal tax-exempt status; preference; protection(a) Revenue bonds issued pursuant to this part, to the extent practicable, shall be issued to comply with requirements imposed by applicable federal law providing that the interest on such revenue bonds shall be excluded from gross income for federal income tax purposes (except as certain minimum taxes or environmental taxes may apply). The department head or presiding officer of the governing body is authorized to enter into agreements, establish funds or accounts and take any action required in order to comply with applicable federal law. Nothing in this part or this chapter shall be deemed to prohibit the issuance of revenue bonds, the interest on which may be included in gross income for federal income tax purposes.(b) For the purpose of insuring that interest on revenue bonds issued pursuant to this part which is excluded from gross income for federal income tax purposes (except as provided in subsection (a)) on the date of issuance shall continue to be so excluded, no state officer or employee, or user of an undertaking or loan program shall authorize or allow any change, amendment, or modification to an undertaking or loan program financed or refinanced with the proceeds of revenue bonds which change, amendment, or modification thereto would affect the exclusion of interest on those revenue bonds from gross income for federal income tax purposes unless the change, amendment, or modification shall have received the prior approval of the department head or chairperson of the governing body. Failure to receive the approval of the department head or chairperson of the governing body shall render any change, amendment, or modification void.