Once again, incorrect tax bills have been sent to some Fulton County property owners.

This time, the burden is on the taxpayers to fix the problem. So far, only homeowners who contested their assessments are affected by the latest errors, but it's unclear how many.

"I don't know what's going on - it's all screwy," Fulton County Taxpayers Foundation Executive Director Barbara Payne said. "But questions need to be answered."

It's the second time this year that Fulton residents have been hit with glitches in the county's tax system. The last round of errors cost taxpayers $140,000 when the county had to remail 230,000 tax assessment notices, correcting omitted and erroneous information from earlier mailings. The full impact could include hundreds of thousands of dollars in lost interest earnings countywide, as cities, school districts and the county will be collecting revenues later.

Barry Levitt, of Sandy Springs, said he'll be making calls to the assessors office on Monday. Surrounded by marked-down and foreclosed homes, he sent in an appeal challenging the county's $422,200 tax value on his house on Redbourne Drive, and said he even received back a letter of acknowledgement from the Board of Assessors.

Still, he got a bill this month for about $5,300 in city and county taxes - calculated at 100 percent - with no reference to his pending appeal.

"Am I surprised? No," Levitt said. "It's typical government. I'm sure they've been swamped this year. I'm going to give them the benefit of the doubt - until Monday."

Anyone who filed an appeal of their property appraisal should take a second look at the tax bills they received this month.

Under state law, if a homeowner files an appeal on time, while the case is pending he or she should receive a temporary bill calculated at just 85 percent of their property's tax value. But dozens of Fulton residents have reported that despite filing the paperwork they're still being billed at 100 percent, according to Payne.

For an Atlanta home valued at $250,000, it would mean county and city tax bills totaling about $3,150 that should be $2,500.

The bigger issue, however, is that an incorrect bill means the Fulton County Board of Assessors Office hasn't processed a homeowner's appeal. Staff could have mis-keyed parcel numbers into the computer system, or documents could have gotten lost or stuck to other pages among stacks of submissions in a record-shattering appeals year, according to Chief Deputy Appraiser Doug Kirkpatrick.

The scope of the problem is difficult to gauge, because the assessors office can't estimate how many appeals weren't entered into the system. Payne, one of the county's most prolific taxpayer advocates, said she has received about 35 to 45 calls within the past two weeks.

The assessors office said it has received three or four calls. The Fulton County Tax Commissioner's Office, responsible for mailing bills based on information provided by the assessors, said it's gotten three calls.

Those affected must prove to the assessors office that they filed on time, with a receipt from the county, a date-stamped copy of their appeal or a certified mail receipt. Someone who sent their appeal in regular mail, then later received a 100 percent tax bill, could be out of luck, Kirkpatrick said.

In May, the assessors office came under fire when about 136,000 Atlanta property owners received assessment notices with inflated estimates of 2011 tax bills, likely the result of a formula error.

The assessors board remailed notices not only to Atlantans, but also to nine cities whose notices didn't include estimates of municipal taxes. That pushed the appeal deadline back five weeks, to July 26, for 70 percent of the county.

Chief Appraiser Burt Manning was not in his office Friday, and efforts to reach him were unsuccessful. His staffers chalked the latest problem up to a 70 percent spike in appeals filed, attributable to both declining property values in the wake of the real estate bust and a new state law requiring that tax notices and estimated bills be sent to every property owner in the county.

According to data Manning provided on Tuesday, Fulton received 35,742 appeals this year, up from about 21,000 in 2010. This year, 8.6 percent of all residential properties and 38.1 percent of commercial properties are under appeal.

"When you have 36,000 of these things coming at you, it's understandable how things can get missed," Kirkpatrick said. "The last thing I want to see is someone lose their right to appeal."

Gwinnett Chief Appraiser Steve Pruitt, whose county's appeals shot from 7,800 in 2010 to 31,162 this year, said his office had all its appeals keyed in by June 15. Tax bills go out Sept. 15. Thanks to a bar code system on appeals forms, his staff was spared having to physically type in parcel numbers.

"I don't see what the problem is of getting every appeal that's filed by the taxpayers keyed into the system," Pruitt said. "If they're not throwing enough resources into that process, then they don't know how many appeals they've got."

Tax Commissioner Arthur Ferdinand said over-billed taxpayers shouldn't fret the extra 15 percent in their tax bills. Once the assessors office finds their appeal and enters it into the system, his office will automatically send a corrected bill. If someone erroneously paid the 100 percent bill, Ferdinand said his office will automatically issue a refund.

County Commissioner Liz Hausmann said that if even 40 people have been affected by another glitch, she's becoming concerned about operations in the assessors office. The commission allocated an extra $1.8 million to it this year so it could cope with an anticipated avalanche of appeals, and so far, the process has been riddled with errors.