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Free Illinois Co-Signer
Guarantor Agreement Template

The guarantor (co-signer), the landlord the guaranty is given to, and the tenant whose lease it backs.

Last reviewed August 2026

Written by LawLease Editorial

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Illinois Co-Signer Guarantor Agreement

This Co-Signer Guarantor Agreement is built with Illinois as the governing state. These are the Illinois landlord-tenant rules that most often bear on it, with the statute for each.

Illinois rules at a glance

Illinois rules for a Co-Signer Guarantor Agreement
Security deposit limitNo statewide cap (Cook County caps at 1.5 months’ rent)
Deposit itemization30 days to give a written itemized statement of damages765 ILCS 710/1
Deposit return45 days for the full deposit if no itemized statement is given765 ILCS 710/1
Deposit interestOnly for buildings of 25+ units on contiguous parcels765 ILCS 715/1
No statewide escrow ruleIllinois does not require a segregated or interest-bearing account statewide. Chicago and Cook County do — and require the tenant be told which institution holds the money.
Late feesNo statutory cap and no mandated grace period

Security deposits in Illinois

Illinois sets no statewide cap on how much a landlord may collect as a security deposit, but it is strict about giving it back. If the landlord withholds anything for damage, a written itemized statement is due within 30 days of the tenant vacating, with paid receipts to follow within a further 30 days. If no itemized statement is furnished at all, the entire deposit must be returned within 45 days (765 ILCS 710/1).

Public Act 103-224, effective January 1, 2024, deleted the old “five or more units” threshold. The Security Deposit Return Act now reaches every residential landlord in Illinois, including someone renting out a single unit.

  • Bad-faith penalty — A landlord who refuses to itemize, itemizes in bad faith, or misses the deadline is liable for twice the wrongfully withheld amount plus court costs and reasonable attorney’s fees (765 ILCS 710/1(b)).
  • Interest is unit-gated — Interest on the deposit is owed only by landlords of buildings or complexes on contiguous parcels with 25 or more units, at the rate paid on passbook savings by the largest Illinois commercial bank, on deposits held more than six months (765 ILCS 715/1). Below 25 units, state law requires no interest at all.
  • No statewide escrow rule — Illinois does not require a segregated or interest-bearing account statewide. Chicago and Cook County do — and require the tenant be told which institution holds the money.

Rent, late fees & increases

Outside Chicago, Cook County and Evanston, Illinois has no law capping residential late fees and no mandated grace period. A late fee is enforceable because it is written into the lease and reasonable — not because it falls under a statutory ceiling. The widely repeated “5% is the legal maximum” figure is industry practice, not Illinois law.

  • Rent increases — There is no Illinois statute setting a rent-increase notice period. For a month-to-month tenancy an increase is a unilateral change of terms, so the 30-day termination notice under 735 ILCS 5/9-207 is used by analogy.
  • Rent control is preempted — The Rent Control Preemption Act bars every Illinois local government from enacting or enforcing rent control (50 ILCS 825/1). The Chicago, Cook County and Evanston ordinances regulate fees and process — not the amount of rent.
  • Coming July 2026 — HB 3564 requires every non-optional fee to appear on the first page of the lease or the tenant is not liable for it, caps application fees at $50, and bans eleven categories of “junk fees.”

Ending an Illinois tenancy

Notice periods turn on the type of tenancy: 30 days for month-to-month, 7 days for week-to-week (735 ILCS 5/9-207), and 60 days for year-to-year, given within the four months preceding the final 60 days of the year (735 ILCS 5/9-205). A fixed-term lease simply expires on its end date unless the lease says otherwise.

  • Nonpayment — A 5-day written demand stating the amount due; the lease terminates if the rent is not paid in full within five days of service (735 ILCS 5/9-209). Late fees are not “rent” and may not be bundled into the demand amount.
  • Other breaches — A 10-day written notice for breaches such as unauthorized occupants or pets, damage, or nuisance (735 ILCS 5/9-210).
  • Jury trial cannot be waived — Either party may demand a jury in a residential possession case notwithstanding any lease waiver (735 ILCS 5/9-108).
  • Safety-related early exit — A tenant facing a credible threat of domestic or sexual violence may terminate under the Safe Homes Act (765 ILCS 750), and a deployed service member may terminate under 765 ILCS 705/16.

Illinois Co-Signer Guarantor Agreement FAQs

How much can a landlord charge for a security deposit in Illinois?

There is no statewide cap — Illinois law limits how the deposit is returned, not how large it is. Suburban Cook County is the exception: its ordinance caps deposits at 1.5 months’ rent and lets the tenant pay any excess in up to six installments.

How long does a landlord have to return a deposit in Illinois?

If the landlord is deducting for damage, a written itemized statement is due within 30 days of the tenant vacating, with paid receipts within another 30 days. If no itemized statement is given, the full deposit is due within 45 days (765 ILCS 710/1). Missing the deadline exposes the landlord to twice the withheld amount plus attorney’s fees.

Does an Illinois landlord have to pay interest on the deposit?

Only if the building or complex has 25 or more units on contiguous parcels (765 ILCS 715/1). Below that, state law requires no interest. Chicago is different — the RLTO requires interest regardless of how many units the building has.

Is there a cap on late fees in Illinois?

Not under state law. Outside Chicago, Cook County and Evanston, Illinois sets no late-fee cap and no grace period — the fee just has to be written into the lease and reasonable. The “5% maximum” often quoted online is industry practice, not a statute.

More Illinois landlord documents

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