Beginning, January 1, 2020, if a worker under 18 works more than 650 hours for the employer during any calendar year, they must be paid the regular (over 18 wage). Tipped employees may be paid 60% of the hourly minimum wage. Certain employees must be paid overtime, at time and one-half of the regular rate, after 40 hours of work in a workweek.
https://www2.illinois.gov/idol/Laws-Rules/FLS/Pages/minimum-wage-rates-by-year.aspx