Can a Illinois landlord raise rent at lease renewal?

Yes. The end of a fixed-term Illinois lease is the typical (and statutorily safest) time for a rent increase. The landlord serves a renewal offer with the new rent, with at least the statutory notice period before the current term ends (Illinois has no statewide advance notice specific to rent increases. 735 ILCS 5/9-207 sets 30 days as the month-to-month termination default, which landlords treat as the minimum for rent changes. No state rent cap; local rent control is preempted statewide.). The tenant has three options: accept and sign for the new term at the new rent, decline and vacate at term end, or stay past term end and convert to a holdover or month-to-month tenancy depending on state law. Where rent control applies, the renewal increase is capped at the statutory annual cap even at renewal. If the tenant continues paying the old rent past the renewal date without signing, Illinois courts often treat this as acceptance of the new rent only if the landlord has given proper written notice and accepted the new payment.

Source: Lease-based; 735 ILCS 5/9-207 (30-day month-to-month termination default)