FIFO inventory accounting assumes that the first items purchased or produced are the first ones sold or used. Therefore, the cost of goods sold reflects the oldest costs of inventory. If a company uses a more expensive shipment of components instead of the lower-cost ones that were previously received, it will increase the cost of goods sold and reduce the gross profit margin. This is because the newer components have a higher unit cost than the older ones, and the cost of goods sold is calculated by multiplying the unit cost by the number of units sold or used. References:

•CPIM Part 1 Exam Content Manual, page 17, section 3.2.1: “Explain the impact of inventory valuation methods (for example, first in, first out [FIFO], last in, first out [LIFO], average cost, standard cost) on financial statements and taxes.”

•CPIM Part 1 Study Guide, page 63, section 3.2.1: “The FIFO method assumes that the first goods purchased or produced are the first goods sold. The cost of goods sold is based on the oldest costs, and the ending inventory is based on the most recent costs. The FIFO method results in a higher net income and a higher ending inventory value in a period of rising prices.”