Credit note and debit note

please  refer  Section  34 of the CGST  act  2017  ( credit  note and debit note ) 

In GSTR1  return  you have  to show in Table  9B   credit  note  debit   notes  and  Table 9C  any amendments  in Credit note , debit notes .  

In GSTR  3B  return  you have  less  credit  note amount  from value of  Taxable supply  and  if debit  note  you have add in value of Taxable supply .