Why two Chicago 3-units collecting identical rents can deliver completely different investment returns.
Three Apartments. $6,000 in Monthly Rent. What Could Go Wrong?
Imagine two 3-units in Chicago. Both contain three two-bedroom apartments. Both are fully occupied, with each apartment renting for $2,000 per month. That’s $72,000 in scheduled annual rent for either building.
But one building has separately controlled heating, newer mechanical systems, and tenants paying their own heating utilities. The other has a central boiler, owner-paid heat, an aging roof, and property taxes that deserve a closer look.
Same rent roll. Very different economics.
The rent roll tells me what comes in. The boiler tells me what stays.
A Chicago Three-Flat Is an Operating Business
When I evaluate a two-flat, three-flat, or four-flat, I want to understand how the entire building operates, not just what the apartments rent for.
Heating is a good example. Some buildings have a furnace and utility account for each unit. Others rely on a central boiler that heats the whole property. Neither configuration is automatically superior. But each creates different expenses, maintenance responsibilities, and replacement risks.
When I’m evaluating a Chicago three-flat with a central boiler, I want to know more than how old the system is. I want to see its service history, annual fuel consumption, recent repair expenses, and anticipated replacement costs. I’m also looking at who’s responsible for paying the heating bills, how efficiently the system operates, and whether major expenses are on the horizon.
Because I’m not just evaluating what the building earns today. I’m evaluating what it will cost my client to own tomorrow.
Chicago’s heating requirements also make the reliability of the system especially important. I would confirm the current applicable standards and the owner’s obligations rather than assume a tenant-paid utility arrangement eliminates the owner’s maintenance responsibilities.
What $72,000 in Rent Might Actually Leave
Here’s an illustrative annual budget for a hypothetical three-flat collecting $2,000 per unit each month. These are assumptions for demonstration, not verified expenses for an actual listing.
| Item | Annual amount |
| Scheduled rent | $72,000 |
| Vacancy and collection allowance (5%) | −$3,600 |
| Property taxes | −$12,000 |
| Insurance | −$4,000 |
| Owner-paid heating | −$6,000 |
| Water and common utilities | −$2,400 |
| Routine maintenance | −$5,000 |
| Management allowance | −$5,000 |
| Capital replacement reserve | −$5,000 |
| Cash remaining before debt service | $29,000 |
That leaves about $29,000 before mortgage payments and income taxes, after the modeled expenses and capital reserve. The $5,000 reserve is a cash-planning allowance, not necessarily a deduction in conventional net operating income (NOI).
If someone excluded both the $6,000 heating cost and the $5,000 reserve, the illustrated cash remaining would appear to be $40,000 instead of $29,000, approximately 38% higher. The rents didn’t change. Only the assumptions did.
The Seller’s Tax Bill Isn’t My Forecast
Property taxes are another area I investigate closely. Cook County uses a triennial reassessment cycle, and Chicago’s next regular reassessment is scheduled for 2027. That doesn’t mean a purchase automatically resets the assessment to the sale price or that every bill will rise. It means I need to understand the property’s assessment history, exemptions, and potential exposure.
If a seller lives in one unit and receives a homeowner exemption, an investor who won’t occupy the building may not qualify for the same exemption. I treat the current bill as a starting point, not a promise about future taxes.
Sometimes the Opportunity Is in the Expenses
Investors often ask whether rents can increase by $100 or $150 per apartment. I ask that, too. But I also want to know whether the building is operating efficiently.
Could better maintenance planning reduce unexpected costs? Is there a heating-system upgrade worth evaluating? Would a utility change actually save money once installation, permits, leases, and ongoing service are considered? Those questions don’t guarantee a better return, but they can reveal opportunities the listing description doesn’t show.
A lower purchase price isn’t automatically a bargain if it comes with a roof, boiler, or masonry project that the underwriting ignores.
What I Want Before My Client Makes an Offer
- Current leases, rent roll, payment history, and security deposit obligations.
- At least 12 months of operating expenses and utility bills, preferably longer.
- Property tax history, exemptions, and insurance details.
- Heating-system configuration, service records, and equipment age.
- Roof, masonry, plumbing, electrical, and other deferred-maintenance information.
- Realistic vacancy, management, maintenance, and capital replacement assumptions.
Then I stress-test the deal. What if a unit sits vacant? What if taxes or insurance rise? What if the boiler needs replacing? I want to know whether the investment still works when conditions are less favorable.
The Takeaway
Chicago’s small multifamily buildings can offer durable income opportunities, but unit count and advertised rents don’t establish investment quality. The relationship between purchase price, operating costs, capital requirements, financing, and long-term demand does.
I’d rather understand a building’s actual operating history than get excited about a projected return nobody has tested.
The rent roll tells me what comes in. The boiler tells me what stays.
See what others miss. Make every move count.
Frequently Asked Questions
What expenses should I expect with a Chicago three-flat?
Common expenses include property taxes, insurance, water, common utilities, maintenance, management, and major repairs. Depending on the building, the owner may also pay for heating and other utilities.
Is a central boiler a bad sign?
No. A properly maintained boiler can be a reliable system. I focus on its condition, operating costs, service history, and replacement outlook rather than assuming one heating configuration is always better.
Does a Chicago property’s tax bill automatically rise after a sale?
No. A sale doesn’t automatically reset the tax bill to a fixed percentage of the purchase price. Assessment changes, exemptions, local levies, and other factors can affect future bills.
What’s the difference between NOI and cash flow?
NOI generally reflects income after vacancy and operating expenses, before debt service and capital expenditures. Cash flow also accounts for financing and other cash obligations. A capital replacement reserve can be useful in cash planning even when it’s not part of conventional NOI.
Are Chicago three-flats good investments?
They can be, but I evaluate each building on its own merits: price, actual income, expenses, condition, financing, and future capital needs.
Related reading: Explore the RL REAL ESTATE Knowledge Base for more on buying, selling, and investing in Chicagoland real estate.
Research resources: Cook County Assessor · Cook County Treasurer · City of Chicago.
