2a reconcialtion

GSTR 2A is auto populated  form GSTR1 filed  by the  supplier , so whatever you have  purchase form supplier  will be reflected in GSTR 2A  therefore  reconcile  GSTR 2A  with  your  purchase  register  also check taken credit in  GSTR3B  form your purchase register . 

Dowload the data of GSTR2A from GSTN and match it with your books using excel formula's. You can also connect with any GSP