gst invoice

NIKUNJ (NIL) (131 Points)

18 August 2018  
I have issued gst invoice in June 2018 with 18% and deposited the same but customer is not ready to accept the gst invoice with18%• so I again issued gst invoice with12% in July. now what is the treatment for refund of that 18%? because I have Shawn 12%gst in gstr1