There are several reasons why an account may need adjustment - to correct an error, for example, or to update a balance before preparing financial reports. However, the nature of accounting requires that every adjustment must be transparent, verifiable, and justifiable. In other words, anyone looking through the accounts should be able to easily identify an adjustment to an account and understand why it was necessary. This guide explains when it is permissible to adjust an account, and how to make that adjustment. It explains the time period assumption, the accrual basis of accounting, as well as the procedure used to close the books at the end of an accounting period.