MUMBAI: Even as bars and restaurants saw a bigger crowd on Saturday night than on Friday, confusion over GST calculation in food bills stumped several patrons.In the earlier system, the value added tax (VAT) was absorbed in menu prices. In other words, it did not reflect in the bills. The addition of 12% to 18% GST, therefore, appeared to be a huge increase over the expected bill amount, though several restaurateurs assure that they have reduced menu prices to factor in the new tax.Several patrons also complained that bars and restaurants continued to levy a 10% service charge, which was recently deemed as voluntary by the Central government.Though GST is a single tax, for the sake of revenue distribution between the state and the Centre, it is equally split into CGST and SCGST. Both must be calculated separately on menu charges and then added to arrive at 12% or 18%, depending on the tax bracket of the establishment. Some eateries went wrong in the calculation of the new tax as they added the SGST amount in the original bill to arrive at the CGST. “Where the GST is 18%, they calculated 9% SGST on a bill of, say, Rs 100, which worked out to Rs 109. They calculated 9% for CGST on this amount—Rs 109 and not Rs 100—and arrived at Rs 118.81. The CGST and SGST amounts did not match,” said Sanjay Kamath, a regular patron at a Matunga finedine.Reacting to the discrepanies, Adarsh Shetty, president of Ahar, an association of over 8,000 bars and restaurants in the city, said he has directed owners of such establishments to correct their software. “While the tax is levied in two equal parts, it has to be calculated separately on the original amount. Most of us are already doing so,” said Shetty while admitting that a sizeable number of restaurants are continuing to levy service charge.