IL 和 cook county 對押金的規定不一樣。

最後一個月的租金實際上屬於security deposit。

IL州法沒有限製押金是多少，所以你可以要三個月。

Cook county要求押金不超過一個半月的租金。所以你最多簽約的時候收兩個半月的錢。

https://securitydepositlaw.com/cook-county-rtlo-2/  see 

Sec. 42-811 – Security Deposit

A. A landlord may not demand or receive a security deposit in an amount in excess of one and one-half months’ rent. A landlord may not avoid the coverage of this subsection by labeling the fee or charge as anything other than a security deposit.