You can make a journal entry for recording decrease in CST by debiting your CST ledger and crediting the applicable expense ledger.
To account for decrease of CST
1. Go to Gateway of Tally > Accounting Vouchers > F7: Journal.
2. Click J: Stat Adjustment to enable the required options in the Stat Adjustment Details screen.
3. Debit the CST ledger grouped and enter the amount.
4. Credit the expense ledger. The journal voucher appears as shown below:
5. Press Enter to save.