For example, if the assessor's office appraises a property at $100,000, then the fair market value must be from $90,000 to $110,000, he said.
The assessor is allowed to use income as a factor in a parcel's worth, and that may be one reason why taxes will increase for more commercial properties than in past years, he said.
However, commercial property values also can increased by 10 percent or more if the owner does not provide income information. That's because the assessor's employees would have to estimate the income, Duffield said.
Anyone wishing to contest a property appraisal can contact the assessor's office, Assessor Sallie Robinson said.
"Our door is always open," she said.
The assessor's office can be reached at 304-357-0250. A contact number also will be listed on the mailed notices, Sluss said.
Property owners also can challenge their appraisals during the Kanawha County Commission's Board of Equalization and Review.
The board will meet every Tuesday and Thursday in the Kanawha County Commission chambers from Jan. 31 to Feb. 26.
Kanawha County commissioners sit on the board.
Commission President Kent Carper said commissioners and the assessor's office have different roles.
"It's their responsibility to do the assessments, and then it's our responsibility to look at each (property owner's) petition and challenge one by one," Carper said.