Expenses relate only to the income statement, expenditure does not. This is why an expense is referred to as a “temporary” account. That is, accounts on the income statement are a snapshot in time, the measurement of what happened in say a month, a quarter or annually.
Breitner and Anthony in their small book outlining an overview of the accounting cycle note, “when an entity acquires a goods or services, it makes an expenditure” (p. 58). The expenditure cited in the book is referring to the acquisition of the goods or materials to be sold, “which will result in the decrease of an asset (cash) or the increase of a liability” (p. 58). In other words, they traded one part of their balance sheet in exchange for another. In this example, cash was decreased and inventory increased. These goods effected the income statement only when they sold. This relates to your cost of goods sold, once those goods sell. When a sale is made, revenue is booked (top line, another temporary account). Your top line is adjusted by the “cost of sales,” in this case, the cost of acquiring the goods, but only the amount that was sold as expressed in monetary measurement (the price at the time of expenditure).
The credit of an asset is only recording its reduction. In the scenario above, goods were sold. This is reflected on the balance sheet to account for the goods that were sold reducing inventory, and the income statement to record the sales revenue (top line), less expenses (including cost of sales), resulting in the bottom line, which is what you ultimately made on the sale.
Reference:
Anthony, R. & Breitner, L. (2010). Core Concepts of Accounting (10th Edition). Upper Saddle River, NJ: Pearson Prentice Hall Publisher.