A cost might be an expense or it might be an asset. An expense is a cost that has expired or was necessary in order to earn revenues. We hope the following three examples will illustrate the difference between a cost and an expense.

A company has a cost of $6,000 for property insurance covering the next six months. Initially the cost of $6,000 is reported as the current asset Prepaid Insurance. However, in each of the following six months, the company will report Insurance Expense of $1,000—the amount that is expiring each month. The unexpired portion of the cost will continue to be reported as the asset Prepaid Insurance.

The cost of equipment used in manufacturing is initially reported as the long lived asset Equipment. However, in each accounting period the company will report part of the asset's cost as Depreciation Expense.

A retailer's purchase of merchandise is initially reported as the current asset Inventory. When the merchandise is sold, the cost of the merchandise sold is removed from Inventory and is reported on the income statement as the expense entitled Cost of Goods Sold.

The matching principle guides accountants as to when a cost will be reported as an expense.