Gst rate wrongly charged

PLS CONFIRM IF I HAVE RAISED A INVOICE AND CHARGED GST 18 % INSTEAD OF 12 % AND IF I DONT WANT TO RECTIFY THE SAME AND BE AS IT IS BCOZ I WILL GET THE PAYMENT AND THE CLIENT WILL AVIAL FULL 18% CREDIT DOES THE DEPARTMENT WILL HAVE ANY PROBLEM WITH THAT IN FUTURE.