It’s relatively straightforward to prepare a report of invoices in number order and have QuickBooks automatically identify missing invoice numbers, such as where there are gaps in the sequence of numbers.
The key to preparing this report is to use another report as a building block. Identifying sequential transactions and those items missing from the list are common requirements for Banking reports. That causes the Missing Checks report to come to mind. This report is found on the Reports->Banking->Missing Checks menu selection.
Let’s start with this report. By default, this report asks you to specify a Bank account. Instead, simply choose an Accounts Receivable account.
With the account selected, set a Filter for the Transaction Type. In the pulldown list on the left side of the Filters window, choose to include transactions having a Transaction Type of Invoice. If you have multiple Accounts Receivable accounts that you’d like to include, you can modify the Filter for Account on this screen as well. Although the Missing Checks report only allows you to select 1 account when first creating the report, you can select multiple accounts at this stage.
To complete the report, change the Report Title on the Header/Footer tab to reflect the actual contents of the report, which is a list of Missing Invoices.
The result is a list of invoices in invoice number order with each break in the sequence marked.
When the report is complete, click the Memorize… button to save these steps that created the report.