State pet-deposit treatment, federal Fair Housing Act assistance-animal rules, and what Illinois landlords can and cannot ask.
Illinois gives landlords real latitude over ordinary pets but almost none over assistance animals. You can ban pets, cap their number, or charge a pet deposit as a matter of business policy. But once a tenant has a disability-related need for a service animal or an emotional-support animal, that animal stops being a pet in the eyes of the law and becomes a reasonable accommodation you generally must grant.
Two layers of law control here. The federal Fair Housing Act (42 U.S.C. 3601 et seq.) and HUD's assistance-animal guidance set the national floor, and Illinois adds the Assistance Animal Integrity Act (310 ILCS 120), effective January 1, 2020, which spells out exactly what documentation you may ask for and what you may not charge. The Illinois Human Rights Act (775 ILCS 5/3-104.1) separately makes it illegal to refuse to rent to someone because they use a guide, hearing, or support dog.
The practical takeaway: your no-pets clause, breed list, and pet fees are enforceable against pets, and unenforceable against a properly documented assistance animal. Getting the distinction wrong is where fair-housing complaints come from.
Illinois has no statewide cap on the security deposit or pet deposit (Chicago RLTO and a handful of other cities have caps). Pet deposits and pet rent are unregulated by state law.
These three words are not interchangeable, and the rules diverge sharply.
Pets are governed entirely by your lease. In Illinois you may prohibit them, limit breed, size, or weight, require a pet deposit or monthly pet rent, and evict for an unauthorized pet. Nothing in state or federal law protects an ordinary pet.
Service animals are defined narrowly. Under the ADA (28 CFR 35.104) a service animal is a dog individually trained to do work or perform a task for a person with a disability (guiding, alerting, retrieving, interrupting a panic episode). In housing, the broader Fair Housing Act standard applies and the animal need not be a trained dog, but the trained-task dog is the clearest case.
Emotional-support animals (ESAs) provide comfort or symptom relief by their presence and need no special training. They are not service animals under the ADA and get no public-access rights to stores or restaurants, but in housing they are treated the same as service animals: a reasonable accommodation you must allow absent a valid reason to refuse.
If the tenant's disability and the animal's connection to it are obvious, you may not ask for proof at all. If the need is not obvious, the Assistance Animal Integrity Act lets you request written documentation of the disability-related need.
That documentation must come from a person with a therapeutic relationship with the tenant. Illinois defines this broadly under 310 ILCS 120: a physician or other medical professional, a mental-health service provider, or a non-medical service agency or reliable third party who has actual knowledge of the person's disability and disability-related need for the animal. The letter must describe the need for the animal, but you may not demand a specific diagnosis or the tenant's medical records.
You may reasonably scrutinize documentation that plainly comes from an online mill with no real relationship to the tenant. What you cannot do is impose your own credentialing rules, require a particular form, or reject a legitimate provider because they are out of state or non-medical.
This is where landlords most often step on a fair-housing landmine. Under the Assistance Animal Integrity Act you may not require a pet deposit, pet fee, or pet-related assessment for an assistance animal, even if you charge every pet owner in the building. The animal is an accommodation, not a pet, and accommodations cannot be surcharged.
You also may not apply breed, size, or weight limits to an assistance animal. A no-pit-bull policy that keeps a tenant's ESA out is not enforceable against a documented assistance animal in Illinois.
What you can do is recover the cost of actual damage the animal causes beyond reasonable wear and tear, whether to the unit or common areas. That comes out of the ordinary security deposit or is billed like any other tenant-caused damage. You just cannot front-load a special charge because an assistance animal is present.
The accommodation duty is strong but not absolute. Under FHA/HUD standards and the Illinois framework, you may deny or withdraw approval of a specific assistance animal when:
A tenant remains responsible for the animal's behavior. If the animal is out of control and the handler does not correct it, or it repeatedly threatens others, you can pursue removal. Illinois also gives you a shield: under 310 ILCS 120 a housing provider is not liable for injuries caused by a tenant's assistance animal that you permitted as a reasonable accommodation.
Handle every request the same way and document each step. When a tenant or applicant asks to keep an assistance animal, treat it as a reasonable-accommodation request, not a lease violation, even if it arrives after a no-pets lease is signed.
If the need is obvious, approve it. If not, ask once, in writing, for documentation of the disability-related need from a provider with a therapeutic relationship. Do not ask for a diagnosis, medical records, or a demonstration of the animal's training. Respond promptly; unreasonable delay can itself be a fair-housing violation.
Approve without a pet deposit, pet fee, breed limit, or weight limit. Keep your normal security deposit and your right to bill actual damage. Put the approval in writing so both sides have a record. If you believe a denial ground genuinely applies, document the specific facts before refusing, and consider engaging counsel, because an assistance-animal denial is one of the most heavily litigated calls a landlord makes.
The most common mistake in Illinois ESA cases is responding with a flat denial, "no pets means no pets", instead of engaging in the interactive process. The interactive process is itself a substantive duty. A landlord who refuses to consider the request, demands more documentation than HUD permits, or imposes a pet fee on an accepted assistance animal will lose at HUD even if the underlying accommodation could have been reasonably denied on its merits.
Pet-related eviction filings correlate with overall landlord-tenant litigation rates. View landlord risk and tenant-law profile by city:
No. Under the Assistance Animal Integrity Act (310 ILCS 120), you may not require a pet deposit, pet fee, or pet-related assessment for an assistance animal, including an ESA, even if you charge every other pet owner. You can still recover the cost of actual damage the animal causes beyond reasonable wear and tear.
If the disability or the disability-related need is not obvious, you may ask in writing for documentation of the need from someone with a therapeutic relationship with the tenant, such as a physician, mental-health provider, or a reliable third party with actual knowledge of the need. You may not demand a specific diagnosis or the tenant's medical records.
No. A properly documented assistance animal is a reasonable accommodation, not a pet, so your no-pets policy, breed list, size cap, and weight limit cannot be enforced against it in Illinois. Those policies still apply to ordinary pets.
Under the ADA a service animal is a dog individually trained to perform a task for a person with a disability, and it has public-access rights. An ESA provides comfort by its presence, needs no training, and has no public-access rights, but in housing both are treated the same under the Fair Housing Act and must be allowed as accommodations.
Yes, but only on narrow grounds: the specific animal poses a direct threat to others' health or safety, or would cause substantial property damage, that cannot be reduced by another reasonable accommodation; the request is an undue financial or administrative burden; or no valid disability-related need exists after you properly request documentation. Denials should be based on the individual animal's conduct, not its breed.
Illinois provides a safe harbor. Under 310 ILCS 120, a housing provider is not liable for injuries caused by a tenant's assistance animal that the provider permitted as a reasonable accommodation. The tenant remains responsible for the animal's behavior and any damage it causes.
Federal authority: 42 U.S.C. § 3604(f)(3)(B); 24 C.F.R. § 100.204; HUD FHEO Notice 2020-01. State authority: 765 ILCS 710 / 765 ILCS 715. Last updated July 14, 2026. For informational purposes only, not legal advice. Pet and assistance-animal questions are highly fact-specific; consult a licensed Illinois attorney before refusing any request.
