The Auto Fill option for CST is available in the Form Issuable/ Form Receivable screen. This option is used to filter the Forms Type and to fill up the form number for a group of vouchers.
Go to Gateway of Tally > Display > Statutory Reports > CST > Form Receivable/ Form Issuable
Press F5: Auto Fill – CST to view Set Form Number screen.
In the Set Form Numbers screen, select the Form from Form Types