The councillor for ward 39 says he has evidence that Uber is "skirting" the tax, and uploaded a letter purportedly from Uber onto his website to prove it.
"I received a copy of an email between an Uber user and Uber indicating that there is no tax charged on the rides," said the councillor. "I do not understand how any company, operating in Canada, can avoid paying the HST."
Karygiannis has demanded an investigation.
"I am totally shocked and surprised that a Canadian corporation is able to get away without charging and paying GST or the HST," Karygiannis said. "Once again, it appears that Uber is skirting Canadian laws and regulations."
Uber says charging HST is up to local and independent driver partners who use their own vehicles to transport passengers.
"As a registered Canadian business, Uber Canada pays all applicable taxes and we regularly communicate to driver partners on how to file their HST as applicable," says Susie Heath, spokeswoman for Uber Canada.
This is one of several attacks on Uber the councillor has registered. He is an unabashed supporter of the taxi industry.