Expenses

Now Marilyn turns to the second part of the income statement—expenses. The December income statement should show expenses incurred during December regardless of when the company actually paid for the expenses. For example, if Joe hires someone to help him with December deliveries and Joe agrees to pay him $500 on January 3, that $500 expense needs to be shown on the December income statement. The actual date that the $500 is paid out doesn't matter—what matters is when the work was done—when the expense was incurred—and in this case, the work was done in December. The $500 expense is counted as a December expense even though the money will not be paid out until January 3. The recording of expenses with the related revenues is associated with another basic accounting principle known as the matching principle.
Marilyn explains to Joe that showing the $500 of wages expense on the December income statement will result in a matching of the cost of the labor used to deliver the December parcels with the revenues from delivering the December parcels. This matching principle is very important in measuring just how profitable a company was during a given time period.

Marilyn is delighted to see that Joe already has an intuitive grasp of this basic accounting principle. In order to earn revenues in December, the company had to incur some business expenses in December, even if the expenses won't be paid until January. Other expenses to be matched with December's revenues would be such things as gas for the delivery van and advertising spots on the radio.