The maximum length of a standard residential lease is one (1) year in Illinois. Leases for longer than one year are valid, but the rental agreement must be in writing.
Verbal leases are enforceable for terms of less than one year, but they are harder to prove. It is recommended that all leases be in writing for maximum legal protection.
If there is no definite term mentioned in the lease (either verbal or written), the tenancy is based on how often rent is paid. Leases can be year-to-year, month-to-month, or week-to-week.
The information for this answer was found on our Illinois Residential Lease Agreement answers.