GSTR-1 how to filed ?

s.murali (commercial manager) (186 Points)

10 March 2018  
Dear All, Month of Dec-17 issue the service tax invoice, tax around Rs.10000/- ,the amount paid.The invoice cancelled inthe month of Jan-18 end.again issues the one more invoice, tax comes around Rs.12000/-.Now filed the GSTR-1 month of Jan-18. How to entered the GSTR-1 .Pl.clarify