For every $10 the city should get in taxes, a little less than a buck never shows.
On Thursday, city officials thanked the 92 percent of Philadelphians who pay their taxes and announced a plan to recoup some of the estimated $492 million in unpaid property taxes that have accumulated over 40 years.
The city issued a request for proposals to create a system for ongoing tax-lien sales.
Councilman Allan Domb, who has been pushing for a program to address tax delinquencies since his Council campaign last year, was joined by Mayor Kenney and Council President Darrell Clarke to announce the initiative.
"We're addressing the 8 percent who don't pay their taxes," said Domb, who stressed that the goal was not to target those who cannot pay.
"Forty percent [of delinquent taxpayers] don't live in Philadelphia, 50 to 60 percent are commercial, investment property owners, so we're doing today the right thing . . . because if we don't collect delinquent taxes, 92 percent are paying for those that don't."
The city conducted two sales of property-tax liens in 2015, generating more than $17 million in collections, mostly from owners who paid to avoid the sale of liens on their property.
Payments were made on more than 2,700 delinquent properties. Liens on 795 properties were sold.
Now the city wants to do even more with a tax-lien sales program carried out in conjunction with the Revenue Department. A vendor could be selected as early as September.
Kenney stood by Domb's side Thursday and insisted "this is not about getting Grandma," but rather, those people who are "thumbing their nose at us, live in other cities, don't pay their taxes."
"It's really important this happens, because I think people are frustrated when they play by the rules and others get away with it," Kenney said.
Domb hopes the city mimics New York, which sold bonds backed by its delinquent taxes, and hired private firms to collect the revenue. New York has provisions to protect low-income and disabled people.
Domb asked the National Tax Lien Association to conduct a study looking at how New York's plan could function in Philadelphia.
The study found Philadelphia could bring in $90 million to $120 million in onetime revenue, according to analysts, and about $30 million a year in new delinquent taxes.