You can return every penny, on time — and still lose in court.

In Chicago, a security deposit isn’t really your money — you’re holding it. The RLTO (the city’s landlord-tenant ordinance) treats it like a loan you didn’t know you took out, with rules most landlords break without ever noticing. The deposit itself is almost never the problem. The paperwork around it is. Here’s the whole machine, so you can see exactly where the teeth are.

Five things the ordinance expects from the second a deposit check clears:

1. Separate account, always. The deposit can’t sit in your operating account — not even “just until things settle.” It has to live in a separate, federally-insured Illinois account, apart from your own money. Commingling is a standalone violation: the tenant doesn’t have to prove they lost a cent. The bank statement tells the story, and “I always meant to move it” isn’t a chapter the judge reads. Where the money has to go →

2. Interest, on the city’s schedule. Hold a deposit past six months and you owe interest — at a rate the City Comptroller resets every single year. Use last year’s rate, skip a year, or “settle up” at move-out instead of paying on schedule, and you’ve created a fresh violation on top of the old one. Late isn’t “even.” Late is its own problem. How the interest works →

3. Receipts and disclosures, on deadlines. You owe the tenant a receipt for the deposit and, within a tight window, the name and address of the bank holding it. Boring, easy to skip — and exactly the technicality that turns a deposit dispute into a deposit lawsuit.

4. The move-out clock is short. Keeping part of it? You get a narrow window to deliver an itemized statement — with the actual receipts or estimates — and a separate deadline to return the rest. Miss it and the right to deduct anything can evaporate, even for damage that was 100% real.

5. Every slip stacks. Here’s the part that stings: these aren’t graded on a curve. Each misstep is its own violation, and the penalty isn’t “give the money back.” It’s return the deposit, plus a penalty of up to twice the deposit, plus the tenant’s attorney’s fees.

Hall of shame: “I did everything right.” — the official slogan of roughly every security-deposit case in Cook County.

Reader Q: A Logan Square landlord asks, “I haven’t paid deposit interest in 8 years. Am I cooked?” The exposure stacks per tenancy, so don’t round it to zero — but don’t panic either. The fix usually starts with the account, not a lawyer.

Every rule above applies to every Chicago landlord. Whether it applies to your units, dates, and bank is the part a newsletter can’t see — that’s what Dweller IQ is for.

The Fine Print is plain-language general guidance, not legal advice — verify against the current ordinance or your attorney before acting on your specific situation.