Indiana Code Title 36. Local Government § 36-9-36-27

Sec. 27. (a) A contractor for an improvement is entitled to monthly estimates of the work done during each month.  The estimates shall be made by the engineer of the unit and approved by the works board.

(b) The works board shall issue to the contractor certificates for eighty-five percent (85%) of the amount due the contractor by the estimates.  The contractor is entitled to receive the amounts named in the certificates in cash or improvement bonds to be collected or issued by the unit.  The certificates are negotiable instruments.