Question29: 
Due to some reasons, i wish to pay less to my foreign supplier (foreign). In that case how to issue debit/credit note and how to show in my GSTR 3B and GSTR 2. Kindly advise on priority.
 

Answer: 
You have two alternatives 

1st No change in GST record

If the credit of the imported input is available then need not to do any change in GST you can take the credit of tax whatever is paid
In this case you may issue debit note for accounting purposes. Foreign exchange would be remitted as per your instructions to the foreign supplier by your banker.

2nd This is a lenghty rout and to be adopted if the credit of import is not available or ITC can not be utilised (LIke in case you are making fabric or railway parts )
In this case you should file a refund claim for the tax higher paid and this refund is available only if the price was charged higher then the actual price 
Refund claim  is to be filed with the custom  (Reply dt. 26/3/2018)