A subsequent assessment may not be levied for any improvement on any property that was within the corporate limits of the municipality on the date of the execution of the first contract for any part of the improvement, unless a special improvement district was originally created for the improvement, and the property on which the subsequent assessment is to be levied was not originally assessed for the improvement but is subsequently included within another improvement district created to finance an improvement that will be connected directly or indirectly with the original improvement. Assessments under this section may be included in a    separate column in the special assessment list prepared for the improvement district and levied upon the properties included in the district at the same time and upon the same notices and hearings as provided by law for the other assessments. A resolution determining the necessity of the improvement must have been adopted in the manner prescribed by law, referring to the designation of the district created for the original improvement and stating that a portion of the cost of the improvement is proposed to be assessed upon property within the improvement district.