Beginning around 2010, 27 buildings in Albany were granted the 485-a tax exemption. It's for condominiums and apartment complexes that are also used for commercial purposes.

The problem is, this exemption was given to buildings that weren't mixed-use, like the 24 condos at 17 Chapel Street. The owners have not paid much in city property taxes, because the tax assessor granted them this exemption. 

Once the assessor became aware of this error, he submitted his retirement notice. But Mayoral candidate Frank Commisso Jr. says it's not just the assessor's fault.

"There is a role that, after they are granted, there is an oversight function, and clearly there was a failure of that function in this instance," said Commisso.

Commisso says Mayor Kathy Sheehan should have known about these mistaken exemptions when she was treasurer in 2010. He also implied she benefited from them, because the company that developed the building at 17 Chapel Street contributed to her campaign.

"It is the sole determination of the assessor to provide the exemption," said Sheehan. "So there's no additional approval that needs to occur. There's no other body that needs to approve that exemption."

Sheehan held a press conference after Commisso's to respond to his attacks.

"People can say anything," said Sheehan. "We are not running a campaign where I'm just willing to say anything. Let's just be really straightforward in all of this: The decision around the interpretation of 485-a was made at least by 2010, long before I ever had the idea to run for mayor of the city of Albany."

She plans to hire an independent auditor to find out if other buildings designated under 485-a don't fit the criteria. Sheehan believes the city lost between $180,000-$240,000 in tax revenue because of the mistake.

Commisso also called on the state comptroller to do an independent audit. The mayor says she would welcome that.