Simplify your subleasing process with our Chicago Sublease Agreement. Easily edit, fill and sign for free with Lumin.Chicago law requires landlords to allow tenants to sublease their apartments if requested. Here's what else you need to know about subleasing in Chicago. This resource provides an example of what a sublease in Illinois looks like. Download. Create your Illinois sublease agreement, and sublet your property. Rent your unit to a subtenant with a sublease agreement form. A sublease agreement is a legal document allowing existing tenants to rent out their rented space to another party, the subtenant. An Illinois sublease agreement is a contract in which an existing tenant (sub-lessor) and a third-party (the sub-lessee) establish a rental arrangement. Complete RLTO Ordinance.