Description: Gaps in the sequence of numbers for Invoice transaction types. This happens most often when someone deletes an Invoice that should have been voided. However, sometimes it is related to invoices that have been issued outside the system, but not yet booked, which leads to understated income and accounts receivable. In more serious cases, it can be used to cover up internal fraud.
Remediation: Ask the members of the team who issue invoices if they know how or why this happened. If you find that the invoice was issued, but not recorded, create an Invoice transaction type to record the transaction in the ledger with the appropriate information. If the invoice needs to be voided, create an Invoice transaction type with that number in the ledger, then void it out so the sequence is preserved.