Who must file Form ST‑556‑LSE? The sales discussed in this guide are sales of items that are simultaneously being leased as part of the same transaction,.A sample lease for tenants and landlords that you can use to create your own version. In this video, we'll dive into the Illinois Commercial Lease Agreement for rental properties. An Illinois commercial lease agreement defines the terms and conditions of a rental arrangement in which commercial property is leased to a tenant. The process of leasing your property begins with getting your prospective tenants to fill out the Illinois rental application. Illinois Compiled Statutes Table of Contents. Landlord. In a commercial lease, the division of responsibilities and obligations between the tenant and landlord is a critical area. Signature lines for both the tenant and landlord, along with spaces for the date. An Illinois lease agreement is a contract that defines the relationship between a property owner and their tenant.