the tax sale funds are first used to pay the existing liens on the property that caused the auction/sale. After that, the original owner is entitled to any remaining funds. They don't get pocketed by the city, at least not initially. The money just kind of...sit there in an account until claimed. According to the article, the combined balance is about $6 million sitting in the account at this time.

>If the funds are not collected by former owners within seven years, the city can seek a court order to access the money for other uses, officials said. But the city hasn’t done that in at least the last dozen years that Scrivener has been with the department, he said. “Money pretty much had been sitting in the account,” said Dorothy Reed, deputy chief of the Bureau of Revenue Collections.

It should be going to the state's unclaimed property fund after 3 years.

Sits in an account for decades