In order for a company's financial statements to be complete and to reflect the accrual method of accounting, adjusting entries must be processed before the financial statements are issued. Here are three situations that describe why adjusting entries are needed:
Not all of a company's financial transactions that pertain to an accounting period will have been processed by the accounting software as of the end of the accounting period. For example, the bill for the electricity used during December might not arrive until January 10. (The reason for the 10-day lag is that the electric utility reads the meters on January 1 in order to compute the electricity actually used in December. Next the utility has to prepare the bill and mail it to the company.)
Sometimes a bill is processed during the accounting period, but the amount represents the expense for one or more future accounting periods. For example, the bill for the insurance on the company's vehicles might be $6,000 and covers the six-month period of January 1 through June 30. If the company is required to pay the $6,000 in advance at the end of December, the expense needs to be deferred so that $1,000 will appear on each of the monthly income statements for January through June.
Something similar to Situation 2 occurs when a company purchases equipment to be used in the business. Let's assume that the equipment is acquired, paid for, and put into service on May 1. However, the equipment is expected to be used for ten years. If the cost of the equipment is $120,000 and will have no salvage value, then each month's income statement needs to report $1,000 for 120 months in order to report depreciation expense under the straight-line method.
These three situations illustrate why adjusting entries need to be entered in the accounting software in order to have accurate financial statements. Unfortunately the accounting software cannot compute the amounts needed for the adjusting entries. A bookkeeper or accountant must review the situations and then determine the amounts needed in each adjusting entry.