Some transactions span more than one accounting period and they require adjustments. Adjustments are necessary for determining key profitability performance measures because they affect net income, assets, and liabilities. Adjustments, however, never affect the cash account in the current period. They provide information about future cash flow. For example, accounts receivable indicates expected future cash inflows.

The four basic types of adjusting entries are:

• Unearned revenues are revenues that are received in cash before delivery of goods/services. These "revenues" are not earned yet and thus should be recorded as liabilities. An adjusting entry should be: a debit to a liability account (e.g., unearned revenue) and a credit to a revenue account (e.g., revenue). Examples are magazine subscription fees and customer deposits for services.

• Accrued revenues are revenues that are earned but not yet received or recorded. They are also called unrecorded revenues. An adjusting entry should be: a debit to an asset account (e.g., accounts receivable) and a credit to a revenue account (e.g., interest revenue). Examples include interest revenues, rent revenues, etc. Such revenues accumulate with the passing of time, but the company may have not received payment or billed the client.

• Deferred expenses are expenses that benefit more than one period. When these assets are consumed, expenses should be recognized: a debit to an expense account and a credit to an asset account. For example, prepaid expenses (e.g., prepaid insurance, rent, etc.) are expenses paid in advance and recorded as assets before they are used or consumed. Another example is depreciation. The cost of a long-term asset is allocated as an expense over its useful life. At the end of each period, a depreciation expense is recorded through an adjusting entry: a debit to a depreciation expense account and a credit to an accumulated depreciation account (a contra account used to total past depreciation expenses on specific long-term assets).

• Accrued expenses are expenses that are incurred but not yet paid or recorded. At the end of the accounting period, the accrued expense is recorded through an adjusting entry: a debit to an expense account (e.g., salaries expense) and a credit to a liability account (e.g., salaries payable). Examples are employee salaries and interest on borrowed money.