In case you want to override the assessable value and tax rate in invoice, allow modification of tax details in F12: configure.
To override the assessable value and tax in an invoice
1. Go to Gateway of Tally > Accounting Vouchers > F8: Sales > Tax Invoice .
2. Click F12: Configure to configure the sales invoice.
3. Select the party ledger in Party's A/c Name option.
4. Enter Party Details , as required.
5. Select the Name of Item from the List of Stock Items . Enter the Quantity and Rate .
6. Select the sales ledger in Accounting Details screen, and press Enter .
7. Click F12:Configure in VAT Details screen.
8. Select the Classification/Nature in VAT Details screen.
9. Enter the required Tax Rate and Assessable Value . The VAT Details screen appears as shown below:
10. Press Ctrl+A to accept the VAT Details screen, and Accounting Details screen.
11. Select the VAT ledger . The sales invoice appears as shown below:
12. Press O to override.