When it comes to building a new $28 million police headquarters, there is no Plan B for what the city will do if the proposed sales tax fails at the ballot on Nov. 4.

Some voters have assumed that city commissioners simply would approve a property tax increase and build the project anyway, if the 0.2 percent sales tax to fund the project doesn’t win voter approval next week. City Manager David Corliss told members of the Lawrence Noon Rotary Club on Monday he wasn’t sure that would be the case.

“We don’t necessarily have a plan if the voters say no,” Corliss said. “We’ll have to step back and re-evaluate.”

City officials earlier this year had roughly estimated that it would require a 3 mill property tax increase to fund an approximately $30 million police headquarters building. The tax increase likely would have to remain on the books for at least 20 years. The price of the project has dropped slightly since that estimate, but the city hasn’t produced a new set of property tax projections.

“We can raise the mill levy without a (citywide) vote, but it would be a significant increase,” Corliss said. “One of the first things you learn on the job as a city manager is that elected officials don’t like to raise the mill levy.”

A three-mill property tax increase on a typical $175,000 Lawrence home would amount to about $60 a year in additional property taxes, and the tax likely would be in place for about 20 years. City commissioners instead are proposing that the project be paid for through a 0.2 percent sales tax increase that would last for a maximum of nine years. The tax would add $20 to every $10,000 worth of taxable purchases made in the city limits.

When the Lawrence chamber of commerce endorsed the sales tax proposal earlier this year, it noted the likelihood of a property tax increase if the sales tax isn’t approved. Corliss did not go that far on Monday.

“You have to ask yourself whether you think the elected officials will raise the mill levy for this type of project,” Corliss said. “They might, but they also might be challenged with some other issues.”

The logistics of any property tax increase also are worth noting. The earliest city commissioners would be able to raise property taxes is for the city’s 2016 budget, Corliss has said. City commissioners begin 2016 budget deliberations in the summer of 2015. There will be a City Commission election that takes place prior to those deliberations. Three of the five seats on the commission — those held by Commissioners Mike Dever, Terry Riordan and Bob Schumm — are up for election. That makes it possible a new commission will be deciding any property tax issue.

“What I can tell you is that if it doesn’t pass, the need doesn’t go away,” Police Chief Tarik Khatib told the Rotary crowd. “Your officers still will go out there and do the best job they can, but we’ll just have to figure out what we’ll do next.”