If a part of a municipality is annexed to another municipality, and if before the annexation the corporate authorities of the divided municipality have made the annual tax levy for the fiscal year in which the annexation occurs, all taxes payable under this levy shall be paid to the treasurer of the divided municipality. But this treasurer shall pay to the treasurer of the annexing municipality that part of all taxes collected on account of the property located in the annexed territory, under the specified levy, as the unexpired part of the fiscal year for the divided municipality bears to its total fiscal year.
65 ILCS 5/7-1-34