65 ILCS 5/9-2-12
An estimate of the cost of the improvement, including the cost of engineering services, as originally contemplated, or as changed, altered, or modified at the public hearing, itemized so far as the board of local improvements thinks necessary, shall be presented to the corporate authorities, except when rendered unnecessary by Section 9-2-9, together with the specified ordinance and recommendation. This estimate of cost shall be presented over the signature of the engineer of the board, if there is one, if not, then of the signature of the president of the board, who shall certify that in his opinion the estimate does not exceed the probable cost of the improvement proposed and the lawful expenses attending the improvement.
However, in a city or village which has adopted or which hereafter adopts the commission form of municipal government, this estimate of cost shall be over the signature of the public engineer, if there is one, and if there is no such public engineer, then over the signature of the mayor or president of that city or village, who shall certify that in his opinion the estimate does not exceed the probable cost of the improvement proposed and the lawful expenses attending the improvement.
The recommendation by the board shall be prima facie evidence that it is based upon a full compliance with the requirements of this Division 2.
In the event the improvement is to be constructed with assistance from any agency of the Federal Government, or other governmental agency, the estimate of cost shall state this fact and shall set forth the estimated amount in dollars and cents that is to be provided by the agency of the Federal Government or other governmental agency.
The commissioners, superintendent of special assessments, or other person appointed to make the assessments as provided hereinafter, shall make a true and impartial assessment upon the petitioning municipality and the property benefited by such improvement, of that portion of the estimated cost that is within the benefits exclusive of the amount to be provided by the agency of the Federal Government or other governmental agency.
65 ILCS 5/9-2-12