35 ILCS 200/20-135
All taxing districts have a vested interest in interest earned by the county collector on all collected but undistributed taxes due the taxing district. The county collector shall maintain an account into which all tax payments shall be deposited when they are available for investment, and from which all interest distribution shall be made in accordance with the provisions of this Section. Taxes collected in counties with a population of less than 3,000,000 shall be invested in accordance with the provisions of Section 1 of the Public Funds Deposit Act. All interest earned on this account shall be disbursed in accordance with the provisions of Section 20-130 to each district which is entitled to receive the interest in the same proportionate ratio that district shared in the distribution of principal taxes to all units of local government.
On or before January 31st of each year the county collector shall file with the Office of the County Clerk and with each taxing district which received interest during the last year, a report identifying each of the receiving taxing districts with the interest amounts paid to each for the entire preceding year.
35 ILCS 200/20-135