Invoice Prefix & Postfix are use to Add text value Before & after Invoice Number Like GST/##/18-19 (Where ## is Invoice Number)
Step 1 : Click on “Setting” menu.
Step 2 : Click on “Invoice Options” menu then go to “Invoice options”.
Step 3 : On Invoice Option page under Invoice Options section you will find a Invoice Prefix & Invoice Postfix.
Invoice Prefix will show before your invoice Number ( Ex : GST/)
Invoice Postfix will show after your invoice Number ( Ex : /18-19)