Under the accrual method of accounting, period costs such as selling, general and administrative expenses are reported on the income statement in the accounting period in which they are used up or expire. They are referred to as period costs because they are not assigned to products, and therefore cannot be included in the cost of items held in inventory.
If a selling, general and administrative (SG&A) expense is prepaid, the prepaid portion will be reported as a current asset. When the prepaid expense expires, it will move to the income statement and become part of that period's SG&A expenses.
Interest expense is also a period cost unless it is determined to be a necessary cost of a self-constructed, long-lived asset.