Mayor Michael Nutter said Tuesday that more than 20,000 people participated in the program, which ran from May 3 through June 25.
Nutter says he's pleased with the results, but that much more needs to be collected as the city continues battling financial deficits.
The city is now planning to step up collection efforts, increase sheriff sales and revoke business licenses as it pursues remaining delinquents.
Nutter says the city also plans to prosecute tax delinquents who do not pay up. He says some delinquents could face up to seven years in prison.
