Evanston residents experienced a double hit where it hurts — this year’s property tax bills.

Despite a Cook County assessor’s warning of a 10 percent to 35 percent increase in assessed valuations this year and a 1.3 percent increase in total property tax rates Evanston City Council passed in February, many residents were unprepared when second installment property tax bills arrived at Evanston homes in early October.

One of these residents is Jeff Cohen, who said he opened his mailbox to find a scary figure staring back.

After seeing a $44,045 equitable assessed valuation, calculated by taking 16 percent of a home’s assessed value, Cohen said his reaction amounted to pure shock, because it had increased more than $23,000 since 2001.

“That’s just off the chart,” Cohen said. “It has no basis in the laws of economics.”

Increases in property valuations can be attributed to factors outside of the home in question, said Kim White of the Cook County assessor’s office.

“Increased home value as well as neighborhood revitalization projects will impact what a property can sell for,” White said.

A home’s property value is directly related to the equitable assessed valuation, which determines what amount homeowners are taxed. The assessments are done every three years.

But Cohen, who purchased his home on the 1200 block of Greenleaf Street in June 2000, said there was no reason for the increase in his assessed valuation. Upon closer inspection of the stated valuation, mailed by the Cook County assessor in May, Cohen noticed errors in the description of his home.

According to Diane Benjamin, assistant to the township assessor, oversights such as Cohen’s have been occurring more frequently and could be costing residents more than their share of the tax burden.

“There are too many mistakes being made,” Benjamin said. “Most of them can be repaired but people have to be vigilant. It takes a lot of work.”

Benjamin said most of the mistakes are found in the assessor’s descriptions of the homes, such as errors in the total square footage or in the home’s characteristics. In Cohen’s case, a stable in the backyard of his 90-year-old home was labeled incorrectly as a garage and his home’s total square footage was measured incorrectly.

“This is an excellent example of what happens when people don’t check the characteristics of their property,” Benjamin said.

Although exemptions for seniors and longtime homeowners can help drive down taxes, mistakes in the assessment could contribute to a tax bill increase.

Unfortunately for Cohen and residents in similar situations, tax bills for 2001 cannot be adjusted. The deadline to appeal an assessed valuation for 2002 was Oct. 4. With Benjamin’s help, residents can try to lower their assessed valuation for 2003, but she said they must begin the appeal process as soon as they notice an error.

“There are all kind of solutions,” she said. “But a person has to be the captain of his own ship.”

White said in some cases the appeal process is an easy one, but it all depends on the original error. Residents can complete appeals as soon as valuations are sent out and are based on the square footage and features of the property — which requires a personal visit.

With property taxes on the rise, Benjamin said she is committed to helping township residents help themselves.

In the past Benjamin has gone to lengths such as traveling to homes to find errors — even if that means taking her own measurements.

“I want this stuff done and I want it done right,” she said.

Cohen is taking a similar approach to his own valuation.

“What you want is equitable treatment,” he said. “And we’re going to fight this … until we reach something I feel is equitable.”