When you delete the last invoice, Instant Invoice automatically resets the invoice serial number counter so that number is reused when you add a new invoice again. When you delete an earlier invoice, this will result in missing invoice number. If you do not want missing invoice numbers, there are a few ways to go about this :
1. Instead of deleting the invoice, simply amend the description in the invoice body to “Cancelled” and adjust its value to zero.
2. If you have already sent out the invoice to the customer. You cannot simply edit the invoice as above. You have to make adjustments using a Credit Note or an invoice with a negative value.
3. If you already deleted the invoice and want to reuse the invoice number :
For example your current invoice number is 1230 but the missing invoice number is 1225
– Click the menu option Tools | Options – Invoice/ Quotations | Invoice. Write down the “Next Invoice Number” on a piece of paper. In our example it should read 1231.
– Amend the “Next Invoice Number” to your missing number. In this example 1225. Click [OK] to accept the changes
– Add a new invoice. You will be given IN1225.
– Before you add another new invoice, go back to the “Next Invoice Number” and change it back to the number you wrote down earlier, 1231 in our example. This step is very important or you will get duplicate invoice numbers