50 ILCS 460/65
If, after final settlement with the contractor for any improvements, there is any surplus remaining, the Board of Local Improvements shall declare a surplus and rebate upon each lot, block, tract, or parcel of land assessed the pro rata proportion of that surplus. The Board of Local Improvements shall state which specific assessment installments (including interest thereon) are being reduced. If the Board of Local Improvements determines these excess amounts have been collected for making, levying, and collecting or for reserves for deficiencies, the governing body can declare a surplus and credit such amount to each lot, block, tract, or parcel of land assessed or a pro rata proportion to the next installment as a partial reduction of the payment due or, alternatively, may use such surplus to retire bonds in any manner so determined.
50 ILCS 460/65