A short form office lease agreement drafted in favor of the landlord for use in a multi-tenant office building in Illinois. In this Standard Document, the tenant pays its proportionate share of the increases in real estate taxes and operating expenses above those expenses incurred in a base year. A lease with this type of escalation payment arrangement is sometimes called a modified gross lease or a base year model gross lease. This Standard Document has integrated notes with important explanations and drafting and negotiating tips for both landlords and tenants.