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.In Chicago, landlords must approve reasonable sublease requests unless the property is owneroccupied with six or fewer units. A sublease, or a sublease agreement, is when a landlord and tenant agree to rent out the unit to another resident not originally on the lease agreement. The Chicago law states that a sublease must be "reasonable" in nature. In Chicago, the legal rights and responsibilities of both landlords and tenants are covered in the Residential Landlord and Tenant Ordinance (RLTO). A sublease agreement is a legal document allowing existing tenants to rent out their rented space to another party, the subtenant. • To maintain the property in compliance with all applicable provisions of the Municipal Code. If there is no such prohibition, then a tenant may sublease or assign their lease to another. In Chicago, the legal rights and responsibilities of both landlords and tenants are covered in the Residential Landlord and Tenant Ordinance (RLTO).