Tenants Must Have Written Permission to Sublet. Without the landlord's consent, any sublease might be unenforceable, potentially leading to legal disputes or eviction.In Chicago, the legal rights and responsibilities of both landlords and tenants are covered in the Residential Landlord and Tenant Ordinance (RLTO). Tenants generally can't sublet their unit without the landlord's consent. Protect your rentals with Avail lease agreements and amendments. Illinois tenants are generally allowed to sublet, unless their lease specifically prohibits it. For example, Chicago landlords are required to approve reasonable sublease requests from tenants. If the original lease allows subletting or doesn't mention it, the tenant can sublease without landlord permission. Tenants generally can't sublet their unit without the landlord's consent. Protect your rentals with Avail lease agreements and amendments.