Illinois Lease Agreement

An Illinois lease agreement is a written contract between a landlord (or property manager) and a tenant that explains all the important rental terms—such as rent amount, due date, lease length, and maintenance responsibilities.

To be legally valid, the lease must follow the Illinois Residential Landlord and Tenant Act (765 ILCS 705). This law protects both landlords and tenants by defining their rights and obligations.

Landlords and property managers in Illinois commonly use a few different types of leases:

• Fixed-Term Lease: Runs for a specific period (for example, 12 months). Rent and terms stay the same until the lease ends.
• Month-to-Month Rental Agreement: Automatically renews every month until either party gives at least 30 days’ written notice to terminate or modify the lease (735 ILCS 5/9-207).
• Sublease Agreement: Allows an existing tenant to rent out the property to another person (a “subtenant”) — but only with the landlord’s written approval.
• Commercial Lease: Used for business properties like offices or storefronts (governed by separate commercial leasing laws).

To make an Illinois lease agreement legally compliant, be sure to include the following details:

• Tenant and Landlord Names: Full legal names of everyone involved.
• Property Address: Full legal address and unit details.
• Lease Term: Start and end dates, along with renewal or termination terms.
• Rent Details: Monthly rent amount, due date, payment methods, and late fee policies.
• Security Deposit Terms: Deposit amount, refund policy, and deductions (Security Deposit Return Act (765 ILCS 710)):
  • Return of the deposit within 30 days (for buildings with 5+ units)
  • Itemized deductions within 30 days
  • Return of any remaining deposit within 45 days
• Illinois Required Disclosures:
  • Lead-based paint disclosures (for properties built before 1978)
  • Radon disclosure for certain residential properties (420 ILCS 46)
  • Shared meter disclosure if utilities are shared (765 ILCS 740)
• Signatures of both parties: Both landlord and tenant must sign and date the lease.

The main difference is the duration, flexibility, and legal obligations under Illinois law:

• Lease Agreement: Usually covers a fixed term (for example, one year). Rent and terms can’t change until the lease ends, unless both sides agree in writing.
• Rental Agreement (Month-to-Month): Typically runs month-to-month and renews automatically. Either party can end it with 30 days’ written notice, and landlords can adjust terms for the next month if they give proper notice (735 ILCS 5/9-207).

No, under the Illinois Residential Landlord and Tenant Act (765 ILCS 705), a landlord cannot increase rent during a fixed-term lease unless the lease specifically allows it.

For month-to-month leases, landlords may raise rent or change other terms, but must give the tenant at least 30 days’ written notice before the next rental period begins (735 ILCS 5/9-207).

If a tenant ends their lease early in Illinois, they may still be financially responsible for paying rent until the lease term ends or until the landlord finds a new tenant.

Under Illinois Residential Landlord and Tenant Act (735 ILCS 5/9-213.1), landlords must make reasonable efforts to re-rent the property to reduce financial loss — this is called “mitigating damages.”

In Illinois, lease renewal and termination depend on the type of lease:

• Fixed-Term Lease:
  • Ends automatically on the stated end date unless both parties agree to renew.
  • Renewals should always be done in writing, either through a new lease or a signed addendum.
  • A tenant or landlord cannot terminate a fixed-term lease early without mutual consent unless there’s a legal reason.
• Month-to-Month Lease:
  • Automatically renews each month until someone gives proper notice.
  • Either landlord or tenant can end the agreement with 30 days’ written notice before the next rental period begins (735 ILCS 5/9-207).

Yes, an Illinois lease agreement can be modified after signing, but only if both the landlord and tenant agree in writing.

Any changes should be added as a lease addendum that clearly describes what’s being modified (for example, a rent change, pet policy, or added occupant). Both parties must sign and date the addendum to make it legally binding and must comply with the Illinois Residential Landlord and Tenant Act (765 ILCS 705).