CHICAGO — Some Chicago-area retailers are expressing uncertainty over how they’ll assess a sweetened beverage tax.

The tax goes into effect Wednesday. However, the future of the tax is uncertain after the Illinois Retail Merchants Association on Tuesday appealed a judge’s dismissal of a lawsuit to bar the tax.

Under the tax, drinks in a bottle, or from a fountain machine, are taxable. But on-demand, custom-sweetened beverages, such as those mixed by a server, aren’t subject to the tax.

Abid Moinuddin owns Chicken Planet in Chicago’s Loop. Soda at the restaurant was $1 a glass with free refills. Now he says he doesn’t know what to charge.

Moinuddin reports he pays $75 for a box of soda mix. Starting Wednesday, he’ll pay $35 more in taxes. He says refills won’t be free.