Which of the following is not considered a capital expenditure?

Capital expenditures are investments in long-term assets that will be used in the operation of a business over several accounting periods. They typically include purchases that enhance the capacity or extend the useful life of assets.

In the context of the options provided, purchasing new machinery and buying a building for operations are both clear examples of capital expenditures because they involve acquiring significant assets that will benefit the company for many years. Similarly, repairing existing equipment can sometimes be classified as a capital expenditure if it extends the asset's life or enhances its value significantly; however, routine repairs that merely maintain the asset are typically considered operating expenses rather than capital expenditures.

On the other hand, purchasing office supplies is not intended to create a long-term asset for the company. Office supplies are consumed in the short term and do not provide benefits over multiple periods, categorizing them as operating expenses rather than capital expenditures. Thus, the distinction lies in the nature and duration of the benefits provided by the expenditure to the company.