AUBURN – One of the city’s best economic development tools is also one of its most confusing, according to Roland Miller.

“If we can’t attract new developments, we don’t get new property value for the city,” Miller, the city’s economic development director told councilors Monday.

Councilors reviewed the progress of the city’s existing TIF districts Monday night, one week before they’re set to approve the latest. That’s an incentive plan that would return $3.3 million in property taxes to help developer George Schott renovate the Auburn Mall and earmark another $9.1 million for road improvements around the city.

The city has 13 existing TIF districts that cover 597 acres. Since 1998, they’ve collected $14 million in property taxes. Of that, $5.7 million has been returned to developers, including Tambrands, American Falcon and Formed Fiber Technologies.

Another $7.3 million has been spent by the city to pave roads, build Festival Plaza and the Mechanics Row parking garage, purchase firetrucks and pay legal and economic development staff salaries.

Each TIF has helped bring development to the city that would have otherwise gone someplace else, Miller said. The 1998 Tambrands TIF helped keep the manufacturer from relocating to New Hampshire, for example.

It’s one of the few tools Maine municipalities have to encourage development.

“And it’s true that if you choose not to do anything to attract new investments, new investments won’t be made,” Miller said.

TIFs also let cities shelter property values from state accounting. Normally, new investment would mean less state revenue for schools and other projects and steeper taxes paid to the counties. But TIFs keep state revenues coming.

But it wasn’t TIFs themselves but the city’s use of them that concerned some councilors and City Council candidates watching in the audience.

Both Councilor Eric Samson and at-large candidate Ron Potvin asked for explanations of the administrative details concerning how they applied for TIFs.

David Burke, another at-large candidate, said he had doubts about encouraging big box retail with tax incentives. Miller’s charts were impressive, but they missed a part of the story.

“What the exhibits don’t show is what might happen if a local restaurant like a Macs Grill or a Village Inn closes because they can’t compete,” Burke said.