Chicago pre-war two-flats and three-flats produce among the highest LTR cost-seg ratios in our network. Engine-derived walkthrough of the multi-unit FF&E + renovation pool dynamic at $545K Logan Square and $425K Pilsen properties.
Before the analysis: the underlying numbers this post draws on come from 5 Chicago-area properties run through the Cost Seg Smart engine, same engine that produces real customer studies. Median Year-1 federal savings is $21,886 at the 37% top marginal bracket with 100% bonus depreciation. Reclassification ratio ranges 11.9% to 17.6%.
Chicago's cost-seg picture has two layers: a clean federal-acceleration story under OBBBA's restored 100% bonus depreciation, and a more complex Illinois state-side picture that's frequently misrepresented elsewhere. Illinois is not fully conforming on federal §168(k). The Illinois Income Tax Act (35 ILCS 5/203) requires addition modifications for federal bonus depreciation with subsequent subtraction modifications that recover the deduction across multiple Illinois tax years, your federal Year-1 cash captures cleanly, but the Illinois-side benefit is spread rather than fully accelerated. A Chicago investor taking $80,000 of accelerated reclassification at the 37% federal bracket...
The remainder of this section drills into the specifics that matter for comparison local data. The five fixtures we ran through the engine for Chicago span $425,000 to $685,000 in purchase price across 5 distinct sub-markets, enough variance to draw real conclusions about which scenarios actually produce cost-seg ROI in this market.
Take the Lincoln Park SFR Flip as our anchor example. Purchase price: $685,000. Built 1908, 1850 sqft, SFR, located in Lincoln Park / Bucktown / Wicker Park.
The engine determined land allocation of 26.5% using statistical methodology, producing a depreciable basis of $503,338. Of that, the engine reclassified $44,233 into 5-year personal property (FF&E, decorative finishes, certain electrical), $36,093 into 15-year land improvements (paving, landscaping, hardscape, site lighting), and the rest into the 27.5-Year Residential Real Property structural category.
That produces a total reclassification ratio of 16.0%. At 100% bonus depreciation and a 37% federal marginal bracket, the illustrative Year-1 federal tax savings is $29,720. That's the headline number for this fixture.
Contrast that with Logan Square Two-Flat Investor: $545,000 in Logan Square / Avondale, built 1922. Here the engine produced a reclassification ratio of 17.4%, higher than the previous example.
Why? Two reasons. First, the land allocation profile is different, 23.2% here versus 26.5% for the previous example. Second, the engine's treatment of duplex interacts with the build-year and FF&E density differently across neighborhoods.
The takeaway: in Chicago, the per-fixture variance is real. A median number (16.0% reclass) hides meaningful variation across sub-markets and property archetypes.
Illinois generally follows federal MACRS rules but is NOT fully conforming on federal §168(k) bonus depreciation. The Illinois Income Tax Act requires addition modifications for federal bonus depreciation, with subsequent subtraction modifications that recover the deduction over multiple Illinois tax years rather than concentrating it in Year 1. For 2025+ acquisitions under OBBBA's 100% federal bonus, the federal §168(k) acceleration captures cleanly in Year 1, but the Illinois-side benefit is spread across multiple years rather than fully accelerated. Verify current-year Illinois treatment with your CPA; IL bonus depreciation conformity has been adjusted multiple times in recent years and continues to evolve through 2026 legislation.
Decoupling: Illinois has historically required IL Schedule M addition modifications for federal bonus depreciation, with corresponding subtraction modifications recovering the deduction over future Illinois tax years. Model federal and Illinois treatment separately, they do not match year-by-year even when the total deduction is equivalent over the property's holding period.
This affects every cost-seg calculation in Chicago. Because Illinois doesn't fully conform, the federal Year-1 figure shown above is only the federal-only portion. The state benefit is smaller (or different) and your CPA will need to manage the addback at filing time.
Chicago Shared Housing Ordinance restricts short-term rental operations within City of Chicago limits, STR registration is required, density caps apply in certain residential zones, and whole-unit non-primary-residence STR operation is largely prohibited. Suburban Cook County, DuPage County, Lake County, and Will County operate distinct regulatory regimes, some more permissive than Chicago proper. For STR-intent buyers, jurisdictional verification matters more than the cost-seg study itself. For LTR investors (the dominant cost-seg-relevant Chicago segment), standard §469 passive-loss rules apply, and real-estate-professional status under §469(c)(7) is the typical path for high-volume operators wanting W-2 offset. The federal §168(k) acceleration captures Year-1 cleanly; the Illinois state-side benefit is spread across multiple tax years per IITA modification rules rather than concentrated in Year 1, model both treatments separately in your CPA workflow.
To run this analysis for your specific Chicago property: the same engine, with your address, year built, square footage, and renovation history. Studies start at $495 for residential under $300K. Audit defense is included with every Cost Seg Smart study.
To run this analysis for your specific Chicago property: the same engine, with your address, year built, square footage, and renovation history. Studies start at $495 for residential under $300K. Audit defense is included with every Cost Seg Smart study.