Mixed-use property: two uses, one parcel, frequent errors
A shop below and a flat above are assessed differently, and the split is often stale.
A building with a shop below and flats above is one parcel with two uses, and it is among the most commonly misassessed property types there is.
Why it goes wrong
Assessment systems want one class per parcel. A mixed-use building does not fit, so it gets whichever class the record-keeper chose — and in Cook County that choice is worth a great deal:
| Class | Use | Assessment level |
|---|---|---|
| 2 | Residential, up to six units | 10% |
| 5a | Commercial | 25% |
A building coded entirely commercial when most of its floor area is residential is being assessed at two and a half times the correct level on that portion.
The argument
Apportionment. The residential portion should be assessed as residential and the commercial portion as commercial, in proportion to their actual use.
To make it you need the floor areas: how many square feet are in residential use, how many in commercial, and how any shared space is allocated. Plans, a measured survey, or a clear annotated sketch.
A worked illustration
Assessed entirely as class 5a at 25% of a $600,000 market value: $150,000 assessed.
Apportioned — 30% commercial at 25%, 70% residential at 10%: (0.30 × 600,000 × 0.25) + (0.70 × 600,000 × 0.10) = 45,000 + 42,000 = $87,000 assessed.
A difference of $63,000 in assessed value, before the equaliser and the rate.
The other errors to check
A unit count that is wrong. In Cook, up to six residential units is class 2; seven or more is class 3. A building on the boundary is worth counting carefully.
A conversion never recorded. A shop converted to a flat, or the reverse, with the class never updated.
Vacant commercial space. Vacancy is a recognised ground and reliably granted where established. A ground-floor unit that stood empty is a separate claim from the classification argument, and both can run at once.
The income question
Where the commercial element is substantial, the assessor may use an income approach on that portion. Then the arguments become the commercial ones — vacancy, expenses, market rent, capitalisation rate — applied to part of a building.
What to do
- Establish the actual floor area in each use, documented.
- Check the class code on the record against what the building is.
- Count the residential units and check the class boundary.
- Document any vacancy separately, with dates.
- Take advice if the commercial share is large — apportionment arguments are technical and the sums are usually worth it.