Today, Spotlight Delaware unveiled a months-long project taking an in-depth look at the data underpinning the state’s first property reassessment in nearly 40 years.
Spotlight’s analysis underscored the concerns raised for months by Wilmington residents, community leaders and city officials: predominantly Black, brown and low-income communities were hit hardest by rising property values and tax bills spurred by the reassessment.
While many expected reassessment to bring new relief to some of the state’s lowest income residents, it actually raised their tax burdens.
The data for the project was compiled through Freedom of Information Act requests made by Spotlight Delaware and mapped in partnership with Tech Impact’s Data Lab.
The following Q & A is meant to inform readers about the map and be transparent about the choices made by Spotlight Delaware and Tech Impact’s Data Lab in its design.
Why did you build this map?
We recognized that the reassessment of every property in Delaware was a seismic event intended to reshape how we fund government services and our school districts, but there was no public accounting for the results of that work in a way that would be easily understood by the public.
We set out to understand how communities fared in the reassessment and whether the micro-level results matched the public beliefs about Delaware.
Where did the data come from?
Beginning in September 2025, Spotlight Delaware submitted Freedom of Information Act requests for the master assessment data from New Castle, Kent and Sussex counties.
In the cases of New Castle and Sussex counties, we acquired parcel-level data from the 2024 tax year and 2025 tax year to compare the work of the reassessment.
Because Kent County completed its work a year earlier, however, its data is from the 2023 tax year and 2024 tax year.
How did you make the map?
In order to translate hundreds of thousands of parcel-level details into a readable map, we contracted with Tech Impact’s Data Lab, a Newark-based initiative that helps government agencies and nonprofits leverage data, artificial intelligence, and machine learning for social good.
It cost Spotlight Delaware about $10,000 in contract costs on top of significant staff time to complete the project.
What are the shapes on the map?
We used Census tracts, which provide a detailed and statistically reliable view of neighborhoods across the state while preserving privacy.
We could have used ZIP codes, which more people may be familiar with, but they often include communities of very different types, which could skew the results.
What does this map show?
These maps are constructed as heat maps, but unlike most heat maps that you have seen before, blue areas don’t always signify that a reduction has occurred.
Because Delaware hadn’t done a reassessment in decades, all property values were set to rise. So the heat map conveys the change in value relative to the median value in the dataset.
That means that red areas are higher than a median value while blue areas are lower than a median value. Most properties saw increases in assessed value due to the nearly 40-year-long gap between reassessments.
Why did you use median values?
We chose to use a Census tract’s median value – or the value at the absolute center of its data set – because it more accurately depicts how a community member might feel about the reassessment.
Using the average value, or the value of all property divided by the number of properties, allows a few large increases or decreases in a data set to skew how it would appear to the public.
What are the three different maps?
The first map is the assessment map, which shows the percentage change for the total assessed value of property in a given Census tract from before reassessment to after.
The second map is the taxation map, which shows the percentage change for the total taxes levied for property in a given Census tract. That includes county, school district and municipal taxes.
The third map is the tax burden map, which shows the percentage change for the calculation of taxes levied versus the assessed value of property for a given Census tract. This is a calculation of what percentage of property value is paid in taxes annually. Essentially, the tax burden map showcases places in Delaware that were more or less impacted by the ramifications of reassessment.
Why do Sussex County and Kent County see larger swings than New Castle County?
That is due in part to how the southern counties previously accounted for their tax rates. Before the reassessment, Sussex County used 50% of a property’s assessed 1976 value for its tax rate, while Kent County used 60% of a property’s assessed 1987 value.
On the other hand, New Castle County previously used 100% of a property’s assessed 1983 value for its tax rate.
Now all three counties will use 100% of assessed value for its tax rates, which means that the southern counties saw bigger jumps to catch up.
Did you account for areas that have seen new construction?
We did. Areas where there is a lot of new construction could have skewed the results if newly improved properties were left in our datasets.
We limited the dataset to properties that existed in both the pre- and post-reassessment years to ensure we were only tracking changes to existing properties.
Did you use the split rate taxes for New Castle County?
We did not. We aimed to check the work produced by Tyler Technologies – which turned over the data seen here as its completed work – not the government intervention that followed.
The decision to increase the taxation on commercial properties was a political reaction to concerns by homeowners and lawmakers, and was only a short-term fix that is due to expire this year.
Can I see my home on this map?
Our map does not go down to the parcel level, but users can get a sense of how their larger community fares compared to others.
There are other available resources to determine your property assessment and tax bill, and those of neighboring properties.
One such website, MyDETax.com, allows you to compare individual parcels.
My property taxes don’t match the map’s conclusions. Why is that?
Our map is not meant to be representative of every property in a jurisdiction, but it allows for a larger comparative look for how different areas of the state are assessed and taxed. The results for each Census precinct is representative of the median property, but that means virtually all others will be some degree above or below it.
