Bonds issued under this chapter, to the extent practicable, shall be issued so as to comply with requirements imposed by valid federal law providing that the interest on those bonds shall be excluded from gross income for federal income [tax] purposes (except as certain minimum taxes or environmental taxes may apply). The director of finance is authorized to enter into arrangements, establish funds or accounts, and take any action required in order to comply with any valid federal law. Nothing in this chapter shall be deemed to prohibit the issuance of bonds, the interest on which may be included in gross income for federal income tax purposes.

For the purpose of ensuring that interest on bonds issued pursuant to this chapter which is excluded from gross income for federal income tax purposes (except as provided above) on the date of issuance shall continue to be so excluded. No county 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 the bonds which change, amendment or modification would affect the exclusion of interest on the bonds from gross income for federal income tax purposes unless the change, amendment, or modification shall have received the prior approval of the director of finance. Failure to receive the approval of the director of finance shall render any change, amendment, or modification void.