Regarding revised return under vat

Dear all,

We have filed VAT Audit report for the F Y 2016-17 in time in Maharashtra. 

There are difference in Sales for every month in Monthly return & Annual Vat Audit Report.

Is it compulsory to file each month return separately with sales & purchases annexure or can we file signly annual return

or else can we file monthly return without sales & purchases annexure

Please guide us