Question89: a) we have not taken input credit in previous months now, can we take it in month of march if yes, how to show it in form GSTR 3B and GSTR!

Answer The credit can be availed as per section 16 (4) upto the furnishing of annual return or return for the month of September after the end of FY to which invoice relates (which ever earlier).
So you can claim credit and it will be shown as purchase in the month in which return is filled. Please note that it is not necessary that sale in account of supplier and purchase in account of receiver are to be booked in the same month. Because of number of reason like inspection, transit time e.tc. , the receiver may record purchase in subsequent months. (Reply dt. 13/4/2018)