input and output vat duty should be adjusted with each other so that net vat refund or payable can be determined. To adjust this, you need to create a voucher class ” vat Adjustment” and should pass a jorunal entry using this voucher class. Only then your vat return/reports will show you a correct picture of vat position Explore Tally.erp 9 
Creating proper duty ledger is important for professional accounting system. Learn how to create excise duty ledger properly. It should be created under the group duty and taxes and not under sales or purchase Explore Tally.erp 9 
Use voucher class for posting entries in tally.for auto duty calculation voucher class, you should create an item with duty details of excise,vat etc. learn how to create such an item ledger with excise, Cess,S.H.E. and vat duty Explore Tally.erp 9 Voucher class are great tools in tally for speedy and error free entry in tally.one such great voucher class is auto duty calculation by which you can set up duty calculation for sales and purchase voucher to avoid any mistake in voucher entry Explore Tally.erp 9 
Multi narration helps an user to write narration for each entry in tally.one voucher can be added in tally with different heads and each head can be filled up with narration for each entry. Explore Tally.erp 9