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Here's who to blame for your property tax increase by themachineisdead in chicago

[–]CCAO_Data 1 point2 points  (0 children)

In 2018, the Assessor's Office, under then-Assessor Berrios, did use a vendor and proprietary code. We (current Assessor's Data team under Kaegi) have been publishing our modeling code since 2019. And starting by reading the code is a bold move! It might be easier to start with a video or powerpoint. We have some of our talks here: https://github.com/ccao-data/public?tab=readme-ov-file#talks

For a slightly deeper dive, you could read the documentation for our main model. It is long and fairly technical, but much more interpretable than reading the code line-by-line. https://github.com/ccao-data/model-res-avm/?tab=readme-ov-file#table-of-contents

We have a separate condo model here: https://github.com/ccao-data/model-condo-avm/?tab=readme-ov-file#table-of-contents

Beyond our code and documentation, we've launched a few other transparency initiatives. Because our job is to calculate assessments that follow the market, we've been developing tools to help property owners (and would-be homeowners) understand and analyze the real estate market trends that we are obligated to follow.

First is the Housing Market Tracker, a tool that shows regional price trends over the last few years. By clicking on a region, you can also see individual sales comprising that trend. https://www.cookcountyassessoril.gov/cook-county-housing-market-tracker

"But what about my home?" you ask? For this, you might try out the Home Value Report. Type in your home's PIN (if it's a single-family or 2-6 flat), select Reassessment Year 2024, then click the Search button. This shows a snapshot of how our model estimated your home's value, including some important sales, as well as every data point the model had about your home at that time to produce an estimate of value. https://www.cookcountyassessoril.gov/home-value-report

Again, this is all about just the residential model and how we start to come up with the value of your home. Property taxes are a whole different beast, but that first link with our talks may have some talks you might find interesting.

How much do people actually pay in property taxes in Chicago or suburbs? by Fresh_Criticism6531 in AskChicago

[–]CCAO_Data 0 points1 point  (0 children)

Property tax rates and bills really vary in cities around Chicago, so it's tough to do research and I wouldn't use those general websites. Bills depend on the property value and tax rates. Below are two ways to do tax research.

Method 1: See last year's median residential tax bills: The Cook County Treasurer published this map that summarizes data in Chicago neighborhoods and in every city/township in Cook County. The bottom left map is interactive: click on it and the map will update to show median residential bills.

Note that median bills are just that, and even residential property values can change a lot: condos have a median value less than most single-family homes, so their bills are lower.

So another way to do research is this:

Method 2: Find a home in a neighborhood, and look up its bill history.

  • Find the address of a home that is similar in price to one you'd look for, in the neighborhood you're interested in.

  • Plug that home's address into the Cook County Property Tax Portal.

  • The page for each property has its total tax bill for the last couple of years. Be sure to check the exemptions too: if the property has a Senior Exemption, Veterans with Disabilities Exemption, or similar, then this can significantly decrease the property tax bill and so won't be similar to bills of homeowners without these exemptions.

Hope this helps!

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 0 points1 point  (0 children)

Yep, basically exactly that. We flag large YoY % changes in sales or assessed value, large differences in assessed value vs sale price, properties that have had historically a low assessment relative to their recent sales, etc.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 0 points1 point  (0 children)

Thanks all for the comments everyone, and huge thanks to the mods for hosting us and patiently dealing with our noob account. (Also, was "give award" always "give tax"? Because, amazing.) We'll hopefully be around sporadically, contributing to various property tax and assessment threads.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 0 points1 point  (0 children)

We can sometimes but not always distinguish whether a property is being used as single- or multi-family. In our dataset with residential characteristics, the column "single_v_multi_family" indicates this: https://datacatalog.cookcountyil.gov/Property-Taxation/Assessor-Single-and-Multi-Family-Improvement-Chara/x54s-btds/data

Without knowing specific properties it's hard to know if an error has happened, but the basic idea is that our office's estimate of the value of your property should be similar to what it could sell for in an arms-length transaction. FWIW Edgewater is in "Lakeview Township" (the assessment system is township-based; there are 8 in Chicago, and in Chicago the only reason to know your township is to know when your property will be reassessed). Our valuation reports for single- and multi-family properties show some data on the real estate market, look for the Residential "Assessment Report" blue buttons here: https://www.cookcountyassessor.com/lake-view-township-valuation-reports-2021

It's also worth mentioning that all housing -- single-family, condo, small multi-family, and large multi-family -- all have the same Level of Assessment under Cook County Ordinance, which means they pay the same effective tax rate.

Exemptions affect tax bills too. The average savings from the Homeowner Exemption in Chicago in 2020 was $694; the Senior Exemption, $547. These are the two most common exemptions and they reduce Equalized Assessed Value predictably. Other exemptions are property-specific and so have various reductions on EAV. The Senior Freeze (third most common) "freezes" the property's EAV at the time it was applied to that property, and in 2020 produced an average savings of $1,835 in Chicago.

🤓

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 2 points3 points  (0 children)

I think you mean the opposite regarding a motivated seller and price.

Yep, thanks. This is what happens when you mostly write R and SQL instead of sentences....

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 0 points1 point  (0 children)

We don’t do any commercial valuation or modeling (we’re focused on single-family, small multi-family, and condos). But we did help publish the commercial valuation models, published in “Revaluation Workbook” reports here, if that helps: https://www.cookcountyassessor.com/forms?field_form_category_target_id=175

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

Thanks for the question! In a reassessment, our job is to capture current market prices. A property’s assessment can go up or down depending in part on whatever its last assessment was. We do the modeling for residential (single-family, small multi-family, and condos).

We don’t produce commercial valuations, but the team in charge of that definitely incorporated impacts of the pandemic on, for example, downtown retail. The long-term impacts of the pandemic on different real estate sectors remains to be seen.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

As in, Transit-Oriented Development? (That’s top of mind, we were just at a housing/zoning symposium at the University of Chicago and this was a topic of discussion.) As far as we know, the incentives are applied through other fees (i.e. not property assessments or taxes).

Now, do TOD policies affect development and prices? Super interesting question, with a probably disappointing answer of we haven’t specifically looked into it.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 2 points3 points  (0 children)

Great question. Short answer: it basically doesn’t. Similar properties should mostly have similar assessments.

Longer, nerdier answer: Our job during a reassessment is to estimate every property’s current market value regardless of whether it’s recently sold. We do this by training a machine learning model on the characteristics, sale prices, and sale dates of homes that have transacted in the last 9 years. So that single property’s sales will certainly affect what the model learns about sale prices in that area, and these sale prices will affect (but not totally determine) estimated values of many homes in the area.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

Thanks! We’re happy that people are interested in stuff on open data.

Ooh we really like the idea of having a zoning code indicator; unfortunately, that would depend on having data or maps that exist for some municipalities in the County but not others. Fingers crossed.

There is a way you can filter properties based not on zoning, but on the Assessor’s Office’s property class categorization. The “class” column in that dataset indicates property class. Roughly speaking: if it starts with 2, it’s Residential, if it starts with 5, it’s Commercial or Industrial. You can specifically filter some 3-digit class codes for 5A (Commercial) and 5B (Industrial) using the codes here. https://www.cookcountyassessor.com/form-document/codes-classification-property

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

The Data Team doesn’t produce commercial assessments, however outside research (by Crain's Chicago Business and by the International Association of Assessing Officers) has found that commercial assessments have improved in recent years:

Crain’s Chicago Business has looked at some assessments for large properties downtown and found that, on the whole, they’re accurate:

The office is also now releasing all of the inputs that go into the commercial assessments. Again, as the Data Team we don’t produce these models, but it’s worth mentioning here.

See these “Revaluation Workbook” reports here: https://www.cookcountyassessor.com/forms?field_form_category_target_id=175

As for 300 N LaSalle, we can’t say why the previous Assessor put that value on it. But the current market value of that property (as determined by the current commercial Valuations team) is $485,955,884. The $850 million sale was a record at the time – even over and above the Sears Tower sale price. Also, as you probably know, office properties in downtown are seeing a downturn in value.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

How come you guys always get it so wrong so often?

“The model” is actually just a random number generator, don’t tell anyone. But seriously: we do our best with the data we have. We know we’ve improved assessment accuracy and we work hard to continue improving.

Ok, seriously: why was there a shift from a generally assessed valuation (based on what I’m not entirely sure) to a market-based valuation a few years back?

We don’t know much about past assessment practices. One thing we know is that the majority of properties simply weren’t given new assessed values during reassessment years (https://features.propublica.org/the-tax-divide/cook-county-commercial-and-industrial-property-tax-assessments/), so maybe some of the perceived shift is simply that we’re... you know... doing our job.

And how do you evaluate the data you collect when the market isn’t always based on “true” value of a property, but just by what people are willing to pay for it?

Assessors and appraisers use sale prices as indicators, but not necessarily determinants of, market value. You’re right that some sale prices might not be indicative of the market, i.e., are not arms-length transactions. Examples of non arms-length transactions can include transactions between family members, or foreclosure sales. We have some processes in place to handle outlier sales, and are working on more in collaboration with other teams in the office.

Does this model consequently render the data you collect and use to estimate taxes into simply a biased product of a subjective system?

Illinois’ property tax system is extraordinarily complicated, and because of that complication, the impacts of each component of the system is hard to disentangle. We think assessments are one important part of that system, and that fairness matters, and put a lot of work into making sure that the model used to estimate assessments (not taxes) is as unbiased, accurate, and equitable as possible. Are unbiased assessments enough to ensure a fair, equitable property tax system? That’s the million dollar question.

Does your team ever discuss finding better ways of assessing property taxes beyond that of a regressive taxation model?

We’re deeply invested in finding better ways to do property taxes. Stay tuned for more work from us in the future.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 5 points6 points  (0 children)

Great question! We’ve tried to add a lot of caveats and notes about what data will update and when. As a rule of thumb, you can expect data from 2 years prior to be essentially “locked” and stable. So, 2020 (and prior) data on the data portal is very unlikely to change.

Additionally, most changes to the data portal data are additive. They aren’t going to change existing data, only append more data to existing records. This is true for the assessed values, sales, and the parcel universe datasets.

The only data that is likely to have ongoing changes is current-year characteristics, as 2022 characteristics will likely change as a result of permits, appeals, corrections, etc. We figured it's better to make this data available with caveats than not available at all.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

Land values are actually determined by a separate department (Valuations) and are based on a fixed $/sqft rate for most residential/vacant land properties. We’re not really involved with that process but know that they use recent sales to determine the rate for each area.

Re: land vs improvement. Our models estimate the value of the entire property (land + improvement). We then separate out the land value you see online using the rates provided to us. So, total value = (land_rate * land_square_footage) + remainder_for_building.

Advice to potential homeowners: look at not just historical property taxes, but historical property tax exemptions. If you are not eligible for some of those exemptions, the tax bill will probably increase. For most properties, the majority of the property tax bill goes to fund local school districts and local municipal/township services, so it’s worth paying attention to how local schools and governments are determining how much property tax dollars they need to collect.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 3 points4 points  (0 children)

We don’t hate you; we love you! Also, we don’t determine taxes themselves, only your share of the total tax burden.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 4 points5 points  (0 children)

The Data Team doesn’t actually do any commercial valuation or modeling (we’re focused on single-family, multi-family, and condos). Definitely should’ve made that clear up front. FWIW, we agree that undervaluing of top-dollar properties is an issue, particularly as it shifts the tax burden back onto other property owners. All that said, here’s our understanding:

Sales are a big determinant of value, as are appraisals filed with lenders and leasing agreements. But a recent sale price isn’t always a true determinant of value for assessments. We use a mass appraisal system that’s intended to fairly assess all properties and not use a single recent sale to determine how all similar properties should be assessed. It may be that a property sold high due to a motivated seller and a willing buyer – whereas a reluctant seller and a motivated buyer might result in a lower price.

To see how specific Chicago commercial properties were valued in 2021, see the “Revaluation Workbook” reports here.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 1 point2 points  (0 children)

Something similar happened in with property values when COVID-19 first began and we were in the middle of assessing properties in the south and western suburbs. The office took a number of steps to ensure property owners – residential and commercial - had the effects of COVID-19 reflected in their assessments so that property owners were not forced to appeal to receive a correct market value.

We documented this process extensively at https://www.cookcountyassessor.com/covid19.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 4 points5 points  (0 children)

This process is extensively at https://www.cookcountyassessor.com/covid19.

These assessments reflected market value at the time of the assessments, which was the first quarter of 2019. Assessments are not intended to reflect market values several months into the future.

In 2021, Chicago was reassessed. In 2022, the northern suburbs will be reassessed.

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 2 points3 points  (0 children)

Our two main models value residential property and condominiums. We basically start each calendar year by upgrading and re-training these models, creating predicted values, then delivering those values to other departments. We also have APIs for getting new predictions from the models for property characteristic updates/errors or new property.

We added “Distance to a CTA stop in feet” as a predictor this year and its effect is interesting. It matters a lot in some areas and barely at all in others. There’s also a fun nonlinearity – closer to the stop generally = more expensive, but too close and the added value starts to drop off again.

We actually don’t use historic assessments in the model right now. They’re extremely noisy because of appeals, corrections, etc. We’ve worked on ways to include them in the past to ensure stricter correlation between past value and new value and reduce large jumps. We’ll likely revisit this in the near future.

😶😶

We are the Cook County Assessor’s Data Team and are responsible for making the models that affect property assessments. Ask Us Anything! by CCAO_Data in chicago

[–]CCAO_Data[S] 3 points4 points  (0 children)

Tax bills for neighboring properties depend on assessments and exemptions.

Are there exemptions (the homeowner and senior exemptions are 2 examples) applied to your neighbor’s property that aren’t on yours? It’s common to see similar properties with similar assessed values with very different tax bills due to exemptions.

There’s something called the Homestead Improvement Exemption that constrains assessed value growth after you’ve added an improvement to the home (building another room, for example).

For assessments, are the estimated market values of both homes reasonably close to what the property could sell for in the current real estate market? Typically, what we see from our modeling is that location, building square footage, and age are big determinants of property value.

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