Income Statements under Absorption Costing and Variable Costing Gallatin County Motors Inc. assembles and sells snowmobile engines If required, round interim per-unit calculations to the nearest cent. c. What is the reason for the difference in the amount of operating income reported in (a) and (b)? Under the revenues. Under method, the fixed manufacturing cost included in the cost of goods sold is matched with the , all of the fixed manufacturing cost is deducted in the period in which it is incurred, regardless of the amount of inventory change. Thus, when inventory increases, the income statement will have a higher operating income. bble costing concept. a. Prepare an income statement according to the absorption costing concept