Chicago shoppers who don't tote their own reusable bags soon may have to pay a city-imposed 7-cent fee for each plastic or paper bag used by the store to pack their goods.



The 7 cents-a-bag fee, which would start next year, is likely to be part of the 2017 budget proposal that the mayor will present to aldermen on Tuesday, an administration source said.



It would serve two purposes: raising revenue to help close a projected $137.6 million budget shortfall and encouraging people to bring their own bags when they shop.



The fee would raise about $13 million a year, with the city receiving about $9.2 million and merchants getting the rest, the source said.



The Illinois Retail Merchants Association backed the bag-fee idea when the City Council in 2014 voted to ban thinner plastic bags in most stores, a prohibition that took full effect last year. At the time, aldermen resisted the bag fee for fear of being accused of further nickel-and-diming Chicagoans.



The ban on thinner plastic bags was designed to protect the environment, but it left many shoppers turning to paper bags and some merchants substituting thicker plastic bags for the traditional thinner ones, partly thwarting its environmental goals.



The fee would be part of a package of fines and fees that the city expects to raise less than $30 million, the source said.



Mayor Rahm Emanuel has said there will be no major tax increases in next year's budget, after the City Council earlier this year voted to impose a new tax on city sewer and water service that will increase those bills by more than 30 percent over the next four years. The $239 million a year it's expected to raise is going to pension contributions.



The city also plans to cut costs by about $30 million, in part through reduced electric, natural gas and fuel expenses. In addition, Emanuel will propose closing tax and fee "loopholes," the source said. And some revenue now is expected to be greater than when the city first projected the shortfall last summer.



But just how Emanuel will fulfill his recent promise to hire 970 additional police officers over the next two years remains unclear. The new budget proposal may not provide the full answer, since the city won't have to foot the entire cost of that effort in 2017.



hdardick@chicagotribune.com