What is a CPI-linked rent increase in Illinois?
A CPI-linked rent increase ties the annual rent adjustment to the federal Consumer Price Index. Illinois statewide rent caps that include a CPI factor (such as California's AB 1482, which uses 5 percent plus regional CPI capped at 10 percent total) measure CPI for the relevant region in the 12 months preceding the increase. A landlord using CPI-linked rent in a non-rent-cap Illinois jurisdiction can use any CPI measure (national, regional, or "all urban consumers" CPI-U), but the lease must specify which one and the calculation method. Tenants should verify the math: published CPI numbers are public on the Bureau of Labor Statistics website, and a 1 percent error in CPI calculation on a 1-year tenancy at $1,500 rent is $180 over-paid. 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.
Source: Lease-based; 735 ILCS 5/9-207 (30-day month-to-month termination default)
This is an informational answer based on Lease-based; 735 ILCS 5/9-207 (30-day month-to-month termination default) as of early 2026. It is not legal advice. Housing law changes year to year and local ordinances (especially in rent-controlled or rent-stabilized cities) can override or add to state law. For contested cases, consult a Illinois-licensed attorney.