Under the accrual basis of accounting, revenues are reported on the income statement when they are earned. (Under the cash basis of accounting, revenues are reported on the income statement when the cash is received.) Under the accrual basis of accounting, expenses are matched with the related revenues and/or are reported when the expense occurs, not when the cash is paid. The result of accrual accounting is an income statement that better measures the profitability of a company during a specific time period.
For example, if I begin an accounting service in December and provide $10,000 of accounting services in December, but don't receive any of the money from the clients until January, there will be a difference in the income statements for December and January under the accrual and cash bases of accounting. Under the accrual basis, my income statements will show $10,000 of revenues in December and none of those services will be reported as revenues in January. Under the cash basis, my December income statement will show no revenues. Instead, the December services will be reported as January revenues under the cash method.
There will be a difference on the balance sheet, too. Under the accrual basis, the December balance sheet will report accounts receivable of $10,000 and the estimated true profit will be added to owner's equity or retained earnings. Under the cash basis, the $10,000 of accounts receivable will not be reported as an asset, and the true profit will not be included in owner's equity or retained earnings.
To illustrate a difference in expenses, we will assume that the heat and light expense that I used in my accounting service is metered by the utility on the last day of the month. The utilities that I used in December will appear on a bill that I receive in January and will pay on February 1. Under the accrual basis of accounting, the utilities that I used in December will be estimated and will be reported as an expense and a liability on the December financial statements. Under the cash basis of accounting, the utilities used in December will be recorded as an expense on February 1, when the utility bills are paid.
For financial statements prepared in accordance with generally accepted accounting principles, the accrual method is required because of the matching principle.