When Brookhaven homeowner Thomas Spencer saw the property tax bill on his three Sunland Drive houses jump 48 to 80 percent this year, he thought that at least he shared the pain with many neighbors.

But not all of them. Looking at tax records, Spencer was surprised to see that several adjacent commercial properties—including the Brookhaven Chamber of Commerce office and the former Mexican consulate complex—had no change in their bills. And those properties’ assessments were less than one of his houses alone.

“It’s a mystery to me,” Spencer said. “It just seems to me be grossly unfair for residential property owners to be paying ever-higher property taxes…[while] at least these commercial properties are having such low assessments.”

He wondered if the reason was “gross incompetence” or worse.

Calvin Hicks Jr., DeKalb County’s chief appraiser, said there’s a simple reason that some commercial property tax assessments didn’t go up: The county chose not to reappraise them.

This year, DeKalb appraisers skipped several types of commercial properties. In an email, Hicks said that “primarily these were apartments, convenience stores, hotels and retail uses.”

The small office building where the Brookhaven Chamber is a tenant falls under the type not appraised. And the former consulate’s value may be depressed by possible contamination, Hicks added.

Hicks said that county appraisers decide which property types to reappraise by comparing real estate sales with current property data.

“I believe staff reviewed market data and indicated the greatest variation between appraisals and market data were in the use types identified,” he said. “We continue to monitor sales and will modify appraisals where warranted.”

However, Hicks did not respond when asked when these commercial property types were last appraised. Those near Sunland Drive have had no change in assessments in four to five years and possibly longer, according to county property records.

While the county skips some commercial reappraisals, its skyrocketing residential assessments have unleashed a wave of appeals. DeKalb’s 17 percent boost in residential property assessments was the highest among metro Atlanta counties, the AJC reported last month.

That boost was even higher in Brookhaven, at nearly 19 percent, Hicks said. Total residential assessments went from about $1.7 billion in 2014 to $2.1 billion this year.

Hicks noted that Brookhaven’s total commercial tax assessments saw an increase on par with residential: about 15 percent. In hard numbers, that’s a boost from about $751 million to about $864 million.

Still, it’s easy to see how the county’s commercial assessing method triggers frustration for Spencer in his corner of Brookhaven at the intersection of Sunland and Apple Valley Road.

Of 18 residential properties around that intersection, none had a decreased assessment and only two did not change—one of them an unbuilt lot. The 16 other properties had an average increase of 42 percent. The lowest was 8 percent. The highest was 142 percent.

Spencer, who runs a real estate development and construction company, lives at 1283 Sunland Drive and owns 1279 Sunland Drive and 1287 Sunland Drive as investment properties. His tax assessments had not changed since 2012. At 1283 Sunland Drive, this year’s assessment went from $73,840 to $133,080.

Meanwhile, the seven commercial properties along Apple Valley Road near Sunland saw no tax-bill change at all. Spencer knows the value of 2565 Apple Valley Road, where the Brookhaven Chamber resides, fairly well—his company owned it until 2006. Records show its assessed value, now $72,000, hasn’t changed since 2011—when it plunged nearly 50 percent.

The Mexican consulate moved out in 2009, leaving behind a 1.3-acre main property at 2600 Apple Valley Road. It last sold in 2010 for $2.5 million, county records show. Its land is valued by the county at $21,300 and buildings at $23,100. Its assessment of $17,760 hasn’t changed since 2010, as far back as online records go.

The property is owned by Rollins Continental, a subsidiary of Atlanta-based Rollins, Inc., the parent company of Orkin pest control and many other firms. Rollins spokesperson Martha Craft said the property taxes are lower because of a successful appeal three years ago.

“In 2012, when Brookhaven incorporated into a city, [the county] reassessed taxes and we filed an appeal,” she said. “That is why our property taxes are lower.”

Hicks said that property “was at one point acquired by a chemical company which released chemicals into the soil. Our records do not reflect the contamination has been removed, but I have asked staff for an update. It was the presence of the contamination which influences the value of the property.”

John Ruch is an Atlanta-based journalist. Previously, he was Managing Editor of Reporter Newspapers.