By Mike Dunn

By Mike Dunn

PHILADELPHIA (CBS) – Philadelphia City Council is threatening to subpoena the Nutter Administration unless aides to the mayor turn over the precise formulas used to create the new and controversial property assessments.

Council members have become increasingly concerned about the accuracy of the more-than-half million property assessments created by the Nutter Administration.

The lawmakers have anecdotal evidence of mistakes in the new property values, though the Administration says the percentage in error falls within accepted industry standards.

Council president Darrell Clarke voiced frustration that the mayor’s office has not unveiled the precise methodology used to create the values.

“We want to know what formula was used. We don’t want to hear the traditional ‘its industry standards.’ We want a detailed account of how, on an individual basis, they got to these numbers,” Clarke explains.

The council president said if the administration doesn’t provide the formula willingly, he might issue a subpoena.

“We have seen some consistent inaccuracies in a lot of these assessments across the city of Philadelphia. People are owed answers; council is owed an answer and we’re going to get some answers,” says Clarke.

The mayor’s press office later said the administration will provide the information to City Council.