"In our opinion, the candidate's campaign expenses ... exceeded the authorized limit by $40,168," said the report from the three-person audit panel.
It means Ford is in an apparent contravention of the Municipal Elections Act.
Ford ran a $1.3-million campaign — but was challenged over money loaned to his campaign by his family company, Deco Labels.
The auditors found that the $77,000 loaned by Deco broke the rules because the campaign did not pay interest on the loan.
In total, the audit uncovered about 100 violations of the Municipal Elections Act.
Ford's brother Doug, who is city councillor, said he and his brother disagree with some of the findings, but in general believe the audits "were very fair."
Doug Ford didn't say what the next step will be, but seemed to indicate his brother will challenge the findings.
"Our interpretation is totally different; 100 per cent different," he told reporters at city hall.
A special prosecutor may now be brought in to sort through the audit findings and decide if further action needs to be taken.
In a statement released by their lawyer, the two men who brought the complaint against Ford — Max Reed and Adam Chaleff-Freudenthaler — said that based on the number of violations uncovered by the audit they "will be requesting the compliance audit committee proceed with prosecution in a timely manner."
Ford could face penalties ranging from a fine all the way to being removed from office — though most political observers say that is unlikely.
Just one week ago, Ford escaped from another threat to his mayoralty when the Ontario Divisional Court ruled in his favour in a conflict of interest case.
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