Depending on how many people are affected by the error, Manning said, the county might send them a single sheet with a corrected tax total.
"At this stage, I just don't know how widespread it is," he said.
A 2010 state law that went into effect this year requires counties to send assessment notices to all property owners, even if values stay the same, a change expected to result in masses of appeals. The notices must include estimated tax bills based on last year's millage rates.
Attorney Carl Crowley, who handles tax appeals, said he's heard complaints from clients and he has his own problem with an Atlanta rental property -- its estimated taxes going from $5,200 to $8,600 even though the fair market value is still $297,300.
He and others who contacted The Atlanta Journal-Constitution said they've sat down with calculators and tried to figure out where the error lies, but nothing makes sense.
"I can't figure out how they messed it up," said Charlie Hyatt, whose notice said taxes on her Virginia-Highland home will jump from $4,300 to $7,300. "But messed it up they did."