The plastic bag levy will be introduced on July 7 after the Legislative Council's endorsement yesterday, but there are doubts about whether the policy will be ready in time.
Lawmakers passed the resolution - which will see a 50-cent charge for each bag - at about 2am yesterday after a 14-hour debate on the budget.
Caroline Mak Sui-king, chairwoman of the Retail Management Association, said the government needed to do a lot of work before the levy came into effect.
Apart from processing more than 2,000 applications from shops that have to register, Ms Mak said it would also be a challenge for the government to educate the public about which stores would impose the levy and on what types of bags.
'Otherwise, it'll be chaotic on July 7... We don't have confidence that the government will get things ready [in less than three months],' Ms Mak said, adding that she did not understand why the levy could not be introduced a month or two later.
Under the law, any retail chain that has five stores, or an individual retailer with a floor size of over 2,000 sq ft, will have to charge the levy if it sells food, medicine and personal care products. Small bags without handles, such as those used for fresh food, will not carry a levy.
It has been estimated that more than 2,000 outlets, including supermarket chains, will be affected in the initial stage. Some retailers can apply for an exemption - for example, areas apart from the supermarket at a department store.