By Dana Kozlov

CHICAGO (CBS) — Thousands of abandoned and vacant properties are costing Cook County taxpayers billions in lost property tax revenue.

As CBS 2 Political Investigator Dana Kozlov reported Friday night, efforts are under way to help get that money back.

They’re just sitting there – vacant, sometimes dilapidated properties that have been abandoned, or empty lots where the structures were cleared away one way or another. Those lots have unpaid taxes attached to them, and according to Cook County Treasurer Maria Pappas, it adds up to $5 billion in lost property tax revenue.

That is more than a fifth of the current Cook County budget.

“If you look at these numbers, they’re frightening,” Pappas said.

So Pappas is trying to get more people interested in buying the properties. Every other year, the county has a so-called scavenger sale – which amounts to an auction of all properties with at least three years of unpaid property taxes.

This year, more than 31,000 properties are on the auction list. Until now, anyone who wanted a copy of that list had to fork over $250.

“So we scratched that,” Pappas said.

It is now free on the county Treasurer’s website, along with an interactive map to make it easier for potential buyers.

“If more people are on the tax sale roles; if more people pay more money, the other people who already live in houses would be paying less,” Pappas said. “So this is a question of economic development.”

Maywood is one of several communities with dozens of properties on the list. Its mayor applauds the Treasurer’s moves. But waiving that $250 fee isn’t as simple as waving a magic wand – because there is a law requiring it.

“My legal department looked at this, and I said, ‘Can I waive this $250 fee?’” Pappas said. “And they said yes.”

Auction bids start at $250. Once a property is purchased, the original owner has a set amount of time to pay the back taxes.

If that does not happen, the property goes to the scavenger buyer, who pays the taxes.

“What you want to do is make it economically attractive for somebody to build on it or to live there,” Pappas said.

The auction will take place at the George W. Dunne Cook County Office Building, 69 W. Washington St., over two weeks beginning on Valentine’s Day. Each day, properties from specific towns and cities will eb auctioned off.