The magnitude of the favorable/unfavorable production-volume variance under absorption costing is affected by the choice of the denominator level used to calculate the budgeted fixed manufacturing cost per unit. Assume the following actual operating information for Stassen in 2020:

Details of the spreadsheet are as follows:
Beginning inventory: 0
Production: 8,000 units
Sales: 6,000 units
Ending inventory: 2,000 units
Selling price: $1,000 per unit
Variable manufacturing cost: $200 per unit
Fixed manufacturing costs: $1,080,000
Variable marketing cost: $185 per unit sold
Fixed marketing costs: $1,380,000.
Note that this is the same data used to calculate the income under variable and absorption costing for Stassen in Exhibit 9-1. As before, we assume that there are no price, spending, or efficiency variances in manufacturing costs.
Recall from Chapter 8 the equation used to calculate the production-volume variance:
The four different capacity-level concepts result in four different budgeted fixed manufacturing overhead cost rates. The different rates will result in different amounts of fixed manufacturing overhead costs allocated to the 8,000 units actually produced and in different production-volume variances. Using the budgeted fixed manufacturing costs of $1,080,000 (equal to actual fixed manufacturing costs) and the rates calculated in section Effect on Budgeted Fixed Manufacturing Cost Rate for different denominator levels, the production-volume variance computations are as follows:
How Stassen treats its production-volume variance at the end of the fiscal year will determine the effect this variance has on the company’s operating income. We now discuss the three alternative approaches Stassen can use to treat the production-volume variance. These approaches were first discussed in Chapter 4.

The table depicts the fixed manufacturing overhead in December 31, 2020, inventory. The details of the table are as follows:

Details of the spreadsheet are as follows:
(A) Theoretical capacity
1. Denominator level in units: 18,000
2. Revenues: $6,000,000
3. Cost of goods sold
• Beginning inventory: 0
• Variable manufacturing costs: 1,600,000
• Fixed manufacturing costs: 480,000
• Cost of goods available for sale: 2,080,000
• Deduct ending inventory: (520,000) in parenthesis
• Cost of goods sold (at standard cost): 1,560,000
• Adjustment for production-volume variance: 600,000
• Cost of goods sold: 2,160,000
4. Gross margin: 3,840,000
5. Marketing costs: 2,490,000
6. Operating income: $1,350,000
(B) Practical capacity:
1. Denominator level in units: 12,000
2. Revenues: $6,000,000
3. Cost of goods sold
• Beginning inventory: 0
• Variable manufacturing costs: 1,600,000
• Fixed manufacturing costs: 720,000
• Cost of goods available for sale: 2,320,000
• Deduct ending inventory: (580,000) in parenthesis
• Cost of goods sold (at standard cost): 1,740,000
• Adjustment for production-volume variance: 360,000
• Cost of goods sold: 2,100,000
4. Gross margin: 3,900,000
5. Marketing costs: 2,490,000
6. Operating income: $1,410,000
(C) Normal capacity utilization:
1. Denominator level in units: 10,000
2. Revenues: $6,000,000
3. Cost of goods sold
• Beginning inventory: 0
• Variable manufacturing costs: 1,600,000
• Fixed manufacturing costs: 864,000
• Cost of goods available for sale: 2,464,000
• Deduct ending inventory: (616,000) in parenthesis
• Cost of goods sold (at standard cost): 1,848,000
• Adjustment for production-volume variance: 216,000
• Cost of goods sold: 2,064,000
4. Gross margin: 3,936,000
5. Marketing costs: 2,490,000
6. Operating income: $1,446,000
(D) Master-budget capacity utilization:
1. Denominator level in units: 8,000
2. Revenues: $6,000,000
3. Cost of goods sold
• Beginning inventory: 0
• Variable manufacturing costs: 1,600,000
• Fixed manufacturing costs: 1,080,000
• Cost of goods available for sale: 2,680,000
• Deduct ending inventor: (670,000) in parenthesis
• Cost of goods sold (at standard cost): 2,010,000
• Adjustment for production-volume variance: 0
• Cost of goods sold: 2,010,000
4. Gross margin: 3,990,000
5. Marketing costs: 2,490,000
6. Operating income: $1,500,000
Note:
Revenues: $1,000 times 6,000 units equals $6,000,000
Variable manufacturing costs: $200 times 8,000 units equals $1,600,000
Fixed manufacturing overhead costs:
$60 times 8,000 units equals $ 480,000
$90 times 8,000 units equals $ 720,000
$108 times 8,000 units equals $ 864,000
$135 times 8,000 units equals $1,080,000
Ending inventory costs:
Sum of $200 and $60 is multiplied by 2,000 units which equals $520,000
Sum of $200 and $90 is multiplied by 2,000 units which equals $580,000
Sum of $200 and $108 is multiplied by 2,000 units which equals $616,000
Sum of $200 and $135 is multiplied by 2,000 units which equals $670,000
Marketing costs:
$1,380,000 plus product of $185 and 6,000 units equals $2,490,000.
In Exhibit 9-7, for example, the $54,000 difference in operating income between master-budget capacity utilization and normal capacity utilization is due to the difference in fixed manufacturing overhead inventoried
To summarize, the common factor behind the increasing operating-income numbers in the columns from left to right in Exhibit 9-4 and Exhibit 9-7 is the increasing amount of fixed manufacturing costs incurred that is included in ending inventory. The amount of fixed manufacturing costs inventoried depends on two factors: the number of units in ending inventory and the rate at which fixed manufacturing costs are allocated to each unit. Exhibit 9-4 shows the effect on operating income of increasing the number of units in ending inventory (by increasing production). Exhibit 9-7 shows the effect on operating income of increasing the fixed manufacturing cost allocated per unit (by decreasing the denominator level used to calculate the rate).
Chapter 8 discusses the various issues managers and management accountants must consider when deciding whether to prorate the production-volume variance among inventories and cost of goods sold or to simply write off the variance to cost of goods sold. The objective is to write off the portion of the production-volume variance that represents the cost of capacity not used to support the production of output during the period. Determining this amount is almost always a matter of judgment.
For financial reporting, SFAS 151 provides greater clarity by requiring that the allocation of fixed manufacturing overheads to production be based on the normal capacity of the facilities. In this case, normal capacity refers to a range of production levels expected to be achieved over a number of periods or seasons under normal circumstances. With abnormally high production, fixed overhead allocated to each unit produced is decreased so that inventories are not measured above cost. When production is below the range of expected variation in output, the unallocated fixed overhead costs are recognized as an expense in the period in which they are incurred. The provisions of SFAS 151 need not be applied to immaterial items. Moreover, the rule does not require disclosure of the dollar amount of any adjustment necessary for compliance, that is, the amount of fixed overhead costs associated with unused productive capacity that is currently expensed to cost of goods sold, rather than included in the ending work-in-process and finished-goods inventories.