That's because the exemption is optional, she said. Owners must apply for it at some point, but can remove it at any time.
"It's a homeowner's wish. If they would like to have the exemption repealed, I'll be happy to do that," she said. Interested homeowners can email Downing's office at email@example.com to request the form.
The generous exemption, by which homeowners older than 62 don't have to pay any school taxes on their property, is part of the reason the Cobb School District is facing a $127 million reduction for its fiscal year 2011 budget.
The school board is expected to approve the $819 million budget at its next meeting, June 9.
"I've received comments that a lot of people think it's too lenient, that they should be paying the tax," Downing said. "I've had a lot of comments from people saying 'I wouldn't mind paying the tax.' It just occurred to me that if there are really people out there that want to pay the tax, it's voluntary."
Currently, 39,171 homeowners in Cobb take advantage of the exemption. Cobb School leaders have said the senior exemption cost the district nearly $64 million in revenue in 2009.
Eligible seniors can reapply for the exemption in later years, if they wish. Applications to receive the exemption are due by April 1 to take effect in the same year.
Board Chairwoman Lynnda Crowder-Eagle said she was unaware that the senior exemption was optional, but doubted that would change the mind of many seniors.
"If there was someone who wanted to forfeit that exemption and allow it to go to us, that would be great," Crowder-Eagle said. "I don't predict that a lot of people will, because in this time, most people feel that they've paid into the school taxes. It's one of those things that I think is very appealing about Cobb County."
Crowder-Eagle said she does not intend to bring up the exemption option at the June 9 meeting.
Downing said her office will remove the exemption of any senior homeowner who notifies her office in writing, and the change will take effect immediately.
Property tax bills will be mailed Aug. 15, as usual. Removal requests can be made at any time, and the tax office will send an adjusted bill, if necessary. For more information, visit www.cobbtax.org or call 770-528-8600.
City of Marietta residents apply for the exemption through the city's tax office, so removal requests must go through there as well. And Marsha Beard, the city's tax manager, said she can recall one or two people asking for their exemption to be removed.
The City of Marietta tax office can be reached at 770-794-5680.