The concept of a unified ledger accounting application is often new to people who have used traditional modular accounting systems, though the idea is very simple. Traditional modular systems have separate General, Purchase and Sales Ledgers which reflect times when accountants wrote information into large paper books or ledgers. Balances on control accounts were copied from one book to another, so that a full set of accounts could be completed and as an additional process control accounts were reconciled. This ensured that all of the individual entries added correctly to the control totals before any transfers were made. In the late 1970s computer experts spotted the potential for writing accounting systems using computer software. Quite rightly they asked accountants what they did and replicated the system of accounting used providing a solution that was easy to understand. This was the birth of modular accounting software which reflects the historic process by either generating information in the background or by batch updates from one ledger to another. What the experts didn’t ask was why accountants had this multiple book system. The reason for which is simply that having a single book would mean that having to accumulate values for what had been bought, sold or received in cash would be extremely difficult to manage and history had taught them how accounting should be done. A unified accounting system works differently; it is a single book in which two entries, a debit and credit, are made at the same time. All of the debits add to the same value as all of the credits. The result is that no control accounts are required and no transfers to other ledger books. There is no requirement for you to reconcile control accounts, and no opportunity for your system to be out of balance. In addition, there are no hidden background processes within software that need to be checked or maintained. Identifying a unified ledger Today, the vast amount of computing power available means that many software vendors claim to have a unified ledger accounting system, when they do not. The processes and hooks generate the additional entries required in the system are fast enough for the user not to notice, so how can you identify whether your accounting system is modular or unified? Duplicate lines One condition of a unified ledger is that if you enter a purchase invoice with three lines, you will