What clauses are legally required in every Illinois lease agreement?
Every Illinois lease should identify the landlord/agent and all adult tenants, the property, the rent and due date, and the term. The most important structural question in Illinois is location: a lease for a Chicago unit must comply with the RLTO (and attach the RLTO Summary), a suburban Cook County unit with the RTLO, and units elsewhere with general state law. Leases longer than one year must be in writing under the Frauds Act (740 ILCS 80); an oral lease over a year is treated as a year-to-year tenancy.
The Rent Concession Act (765 ILCS 730) also requires that any rent concession be noted on the lease with the words "Concession Granted" — omitting it is a Class A misdemeanor.
Illinois security deposit rules — statewide vs. Chicago and Cook County
Statewide: Illinois sets no deposit cap. The Security Deposit Return Act (765 ILCS 710) applies to landlords with 5 or more units: the landlord must furnish an itemized statement of damages within 30 days and return the balance within 45 days of the tenant vacating; noncompliance exposes the landlord to the deposit plus twice the amount wrongfully withheld plus attorney's fees. The Security Deposit Interest Act (765 ILCS 715) requires interest only for buildings/complexes of 25 or more units on deposits held more than six months.
Chicago (RLTO, Municipal Code ch. 5-12): a written deposit receipt is required; the deposit must be held in a separate, federally insured, interest-bearing Illinois account with no commingling; interest is paid annually at the City-published rate; the deposit must be returned within 45 days with a 30-day itemization; and violations expose the landlord to twice the deposit plus interest and fees. The RLTO Summary and the current Security Deposit Interest Rate Summary must be attached to the lease.
Suburban Cook County (RTLO, effective June 1, 2021): caps the deposit at 1.5× monthly rent, requires a receipt and a 30-day return, and excludes owner-occupied buildings of six or fewer units and municipalities with their own ordinance (Chicago, Evanston, Mount Prospect).
Late fees and rent rules in Illinois
Statewide: Illinois has no statutory residential late-fee cap; late fees are governed by a common-law "reasonableness" standard (roughly 5% of rent is a common benchmark). Note: the "$20 or $20 plus 20%" formula that circulates online is from the Self-Service Storage Facility Act (770 ILCS 95) and does not apply to residential leases.
Chicago (RLTO): late fees are capped at $10 per month on the first $500 of rent, plus 5% of any rent above $500. An excess fee is void and can expose the landlord to two months' rent plus fees.
Notice periods to end or not renew an Illinois lease
Illinois notice periods (Code of Civil Procedure, 735 ILCS 5):
| Situation | Notice | Statute |
|---|---|---|
| Terminate month-to-month (either party) | 30 days | 735 ILCS 5/9-207 |
| Terminate year-to-year | 60 days | 735 ILCS 5/9-205 |
| Nonpayment of rent | 5-day written notice | 735 ILCS 5/9-209 |
Chicago and some suburbs add local rules (for example, longer notice for large rent increases and required disclosures), so confirm the local ordinance for the property's location. Self-help eviction is unlawful throughout Illinois.
What disclosures must Illinois landlords provide?
Key Illinois disclosures:
- Safer Homes Act summary (765 ILCS 752, effective Jan. 1, 2026): attach the Illinois Department of Human Rights (IDHR) Summary of Rights as the first page of every written lease and renewal, and obtain the tenant's signature at the bottom of each page of the summary.
- Lead-based paint (federal): signed disclosure, records, and the EPA pamphlet for pre-1978 housing.
- Radon (Illinois Radon Awareness Act, 420 ILCS 46): the landlord must give the "Radon Guide for Tenants" and a radon disclosure form, and share any records showing a radon hazard, for units below the third story.
- Chicago RLTO Summary and the Security Deposit Interest Rate Summary attached to every Chicago lease.
- Rent concession: "Concession Granted" noted on the lease (765 ILCS 730).
See our Illinois required lease disclosures guide for the full checklist and the five mistakes that cost landlords.
What happens if an Illinois lease is missing required terms?
Consequences depend on the rule and the location:
- Statewide deposit (5+ units): missing the 45-day return or 30-day itemization exposes the landlord to the deposit plus twice the wrongfully withheld amount plus fees (765 ILCS 710).
- Chicago RLTO: deposit and disclosure violations carry a 2× deposit penalty plus interest and fees.
- Rent concession: omitting "Concession Granted" is a Class A misdemeanor.
Managing rentals in more than one state? Compare Illinois's split system with our New York and Ohio lease requirement guides.
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Create your Illinois lease agreement →Frequently asked questions
Is there a security deposit limit in Illinois?
There is no statewide cap. But suburban Cook County's RTLO caps deposits at 1.5 times monthly rent, and Chicago's RLTO imposes receipt, interest, and separate-account rules. Which applies depends on the property's location.
How long does an Illinois landlord have to return a security deposit?
Statewide, a landlord with 5 or more units must itemize deductions within 30 days and return the balance within 45 days of the tenant vacating (765 ILCS 710). Chicago's RLTO also uses a 45-day return with a 30-day itemization.
Is there a late-fee cap in Illinois?
Not statewide — late fees just have to be reasonable and in the lease. In Chicago, the RLTO caps late fees at $10/month on the first $500 of rent plus 5% of any rent above $500. The "$20 plus 20%" rule online is a self-storage law, not a residential rule.
How much notice is required to end a month-to-month tenancy in Illinois?
Thirty days' written notice by either party (735 ILCS 5/9-207). Nonpayment of rent requires a separate 5-day notice (735 ILCS 5/9-209).
What disclosures must an Illinois landlord give?
Federal lead-based paint for pre-1978 housing; the Illinois Radon Awareness Act disclosure (420 ILCS 46) for units below the third story; and, in Chicago, the RLTO Summary and Security Deposit Interest Rate Summary attached to the lease.
Official sources
Primary statutes and official government references for this guide. Statutes change — always confirm against the current official text before you act.