wrong hsn code filed at the time of registration

Dear Sir/Mam;
I had filed wrong hsn code at the time of registration. for eg my client is a handloom cloth manufacturer having the turnover below 1.5 crore and the rate of tax levy on him is 5% and I had filed the hsn code of 12% so in this case can I make the tax invoice @ of 5% and filed the gst return for the same which is actual and please let me know what will be the future complication and the proceeding if any for the same.