You can create a journal voucher to decrease output tax.
To create journal voucher for decreasing output tax
1. Go to Gateway of Tally > Accounting Vouchers > F7: Journal.
2. Click J: Stat Adjustment to enable required options in Stat Payment Details screen.
3. Debit the VAT ledger created under the group Duties & Taxes.
o Enter the Rate and Assessable Value in the VAT Details screen.
o Press Enter to return to voucher screen.
4. Enter the amount in Debit column.
5. Credit the ledger created under the group Current Liabilities.
The journal voucher appears as shown below:
6. Press Enter to save.