In case you want to alter the assessable value and tax rate in invoice, allow modification of tax details in F12: configure.
To alter the assessable value and tax in an invoice
1. Go to Gateway of Tally > Accounting Vouchers > F8: Sales .
2. Click I :Item Invoice to record the sale in the item invoice mode.
3. Click F12: Configure .
o Set the option Use common ledger A/c for item allocation? to No .
o Set the option Allow modification of Tax Details for VAT? to Yes .
4. Select the party ledger in Party's A/c Name option.
5. Enter Party Details , as required.
6. Select the Name of Item from the List of Stock Items .
7. Enter the Quantity and Rate .
8. Select the sales ledger in Accounting Details screen.
9. Click F12: Configure in VAT Details screen and enable the following options:
o Allow override Assessable Value?
o Allow override Tax Rate?
10. Select the Classification / Nature in VAT Details screen.
11. Enter the required Tax Rate and Assessable Value . The VAT Details screen appears as shown below:
12. Press Ctrl+A to accept the VAT Details screen. Similarly, accept the Accounting Details screen.
13. Select the CST Ledger . The sales invoice appears as shown below:
14. Press Enter to save.