The sales journal or day book is intended to record individual sales on credit. The originating document for entries in the sales journal is a copy of the invoice sent to the customer.

A sales invoice is made out, normally by the sales department:
a. On notification from the works that the article required has been completed and has been passed to the warehouse for despatch
b. For stock items on the basis of the sales department’s prior knowledge of stock held. In each case an order will have been previously passed to the works or stores specifying the goods required and the customer’s requirements as to packing and delivery. A copy of the delivery note attached to the goods is passed to the sales department for checking against the customer’s order and as a basis for preparing the sales invoice.

In the majority of businesses, large or small, it is necessary to analyze sales by types. The sales journal requires to be similarly analyzed so that totals, say monthly, of each kind of sale, may be posted to the credit of the various sales accounts. The corresponding double entries are made to the individual customer’s accounts in the ledger.