8.4: Compute and Evaluate Overhead Variances

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Recall that the standard cost of a product includes not only materials and labor but also variable and fixed overhead. It is likely that the amounts determined for standard overhead costs will differ from what actually occurs. This will lead to overhead variances.

Determination and Evaluation of Overhead Variance

In a standard cost system, overhead is applied to the goods based on a standard overhead rate. This is similar to the predetermined overhead rate used previously. The standard overhead rate is calculated by dividing budgeted overhead at a given level of production (known as normal capacity) by the level of activity required for that particular level of production.

\[\text {Standard Overhead Rate} = \dfrac{\text {Budgeted Overhead Rate}}{\text {Level of Activity}}\]

Usually, the level of activity is either direct labor hours or direct labor cost, but it could be machine hours or units of production.

Creation of Flexible Overhead Budget

To determine the overhead standard cost, companies prepare a flexible budget that gives estimated revenues and costs at varying levels of production. The standard overhead cost is usually expressed as the sum of its component parts, fixed and variable costs per unit. Note that at different levels of production, total fixed costs are the same, so the standard fixed cost per unit will change for each production level. However, the variable standard cost per unit is the same per unit for each level of production, but the total variable costs will change.

We continue to use Connie’s Candy Company to illustrate. Suppose Connie’s Candy budgets capacity of production at $100\%$ and determines expected overhead at this capacity. Connie’s Candy also wants to understand what overhead cost outcomes will be at $90\%$ capacity and $110\%$ capacity. The following information is the flexible budget Connie’s Candy prepared to show expected overhead at each capacity level.

Percent of capacity: 90 percent, 100 percent, 110 percent respectively. Direct labor hours 1,800, 2,000, 2,200. Units of output 900, 1,000, 1,100. Variable overhead $3,600, 4,000, 4,400. Fixed overhead $6,000, 6,000, 6,000. Total overhead $9,600, 10,000, 10,400. Normal capacity equals 100 percent and overhead is applied based on direct labor hours. Standard Overhead Rate equals $10,000 divided by 2,000 equals $5 per direct labor hour. — Figure $\PageIndex{1}$: Flexible budget for Connie’s Candy

Units of output at $100\%$ is $1,000$ candy boxes (units). The standard overhead rate is the total budgeted overhead of $\$10,000$ divided by the level of activity (direct labor hours) of $2,000$ hours. Notice that fixed overhead remains constant at each of the production levels, but variable overhead changes based on unit output. If Connie’s Candy only produced at $90\%$ capacity, for example, they should expect total overhead to be $\$9,600$ and a standard overhead rate of $\$5.33$ (rounded). If Connie’s Candy produced $2,200$ units, they should expect total overhead to be $\$10,400$ and a standard overhead rate of $\$4.73$ (rounded). In addition to the total standard overhead rate, Connie’s Candy will want to know the variable overhead rates at each activity level.

Using the flexible budget, we can determine the standard variable cost per unit at each level of production by taking the total expected variable overhead divided by the level of activity, which can still be direct labor hours or machine hours.

\[\text {Variable Overhead Rate} = \dfrac{\text {Budgeted Variable Overhead}}{\text {Level of Activity}}\]

Looking at Connie’s Candies, the following table shows the variable overhead rate at each of the production capacity levels.

Table $\PageIndex{1}$: Connie’s Candies variable overhead rate at each of the production capacity levels
Production Capacity	Variable/Unit
90%	$3,600/1,800 = $2
100%	$4,000/2,000 = $2
110%	$4,400/2,200 = $2

Sometimes these flexible budget figures and overhead rates differ from the actual results, which produces a variance.

Determination of Variable Overhead Variances

There are two components to variable overhead rates: the overhead application rate and the activity level against which that rate was applied. If we compare the actual variable overhead to the standard variable overhead, by analyzing the difference between actual overhead costs and the standard overhead for current production, it is difficult to determine if the variance is due to application rate differences or activity level differences. Thus, there are two variable overhead variances that will better provide these answers: the variable overhead rate variance and the variable overhead efficiency variance.

Determination of Variable Overhead Rate Variance

The variable overhead rate variance, also known as the spending variance, is the difference between the actual variable manufacturing overhead and the variable overhead that was expected given the number of hours worked. The variable overhead rate variance is calculated using this formula:

\[\begin{align} \begin{array}{c} \text{Variable Overhead} \\ \text { Rate Variance}\\ \end{array} &= \left (\begin{array}{c} \text{Actual Hours Worked } \\ \times\\ \text {Actual Variable Overhead Rate per Hour }\\ \end{array} \right ) - \left (\begin{array}{c} \text{Actual Hours Worked } \\ \times\\ \text {Standard Variable Overhead Rate per Hour}\\ \end{array} \right ) \end{align}\]

Factoring out actual hours worked, we can rewrite the formula as

\[\begin{align} \begin{array}{c} \text{Variable Overhead} \\ \text {Rate Variance}\\ \end{array} &= \left (\begin{array}{c} \text{Actual Variable} \\ \text {Overhead Rate}\\ \end{array} - \begin{array}{c} \text{Standard Variable} \\ \text {Overhead Rate}\\ \end{array} \right ) \times \begin{array}{c} \text{Actual Hours } \\ \text {Worked}\\ \end{array} \end{align}\]

If the outcome is favorable (a negative outcome occurs in the calculation), this means the company spent less than what it had anticipated for variable overhead. If the outcome is unfavorable (a positive outcome occurs in the calculation), this means the company spent more than what it had anticipated for variable overhead.

Connie’s Candy Company wants to determine if its variable overhead spending was more or less than anticipated. Connie’s Candy had this data available in the flexible budget:

Percent of capacity: 100 percent. Direct labor hours 2,000. Units of output 1,000. Variable overhead 4,000. Fixed overhead $6,000. Total overhead $10,000. — Figure $\PageIndex{2}$: Data from Connie’s Candy flexible budget

Connie’s Candy also had this actual output information:

Percent of capacity: 100 percent. Direct labor hours 2,500. Units of output 1,000. Variable overhead 7,000. Fixed overhead $6,000. Total overhead $13,000. — Figure $\PageIndex{3}$: Connie’s Candy actual output information

To determine the variable overhead rate variance, the standard variable overhead rate per hour and the actual variable overhead rate per hour must be determined. The standard variable overhead rate per hour is $\$2.00$ ($\$4,000/2,000$ hours), taken from the flexible budget at $100\%$ capacity. The actual variable overhead rate is $\$2.80$ ($\$7,000/2,500$), taken from the actual results at $100\%$ capacity. Therefore,

\[\text { Variable Overhead Rate Variance }=(\$ 2.80-82.00) \times 2,500=\$ 2,000( \text { Unfavorable) } \nonumber \]

This produces an unfavorable outcome. This could be for many reasons, and the production supervisor would need to determine where the variable cost difference is occurring to make production changes.

Let us look at another example producing a favorable outcome. Connie’s Candy had this data available in the flexible budget:

Connie’s Candy also had this actual output information:

Percent of capacity: 100 percent. Direct labor hours 2,000. Units of output 1,000. Variable overhead 3,500. Fixed overhead $6,000. Total overhead $9,500. — Figure $\PageIndex{5}$: Connie’s Candy actual output information

To determine the variable overhead rate variance, the standard variable overhead rate per hour and the actual variable overhead rate per hour must be determined. The standard variable overhead rate per hour is $\$2.00$ ($\$4,000/2,000$ hours), taken from the flexible budget at $100\%$ capacity. The actual variable overhead rate is $\$1.75$ ($\$3,500/2,000$), taken from the actual results at $100\%$ capacity. Therefore,

\[\text { Variable Overhead Rate Variance }=(\$ 1.75-\$ 2.00) \times \$ 2,000=-\$ 500 \text { or } \$ 500 \text { (Favorable) } \nonumber \]

This produces a favorable outcome. This could be for many reasons, and the production supervisor would need to determine where the variable cost difference is occurring to better understand the variable overhead reduction.

Interpretation of the variable overhead rate variance is often difficult because the cost of one overhead item, such as indirect labor, could go up, but another overhead cost, such as indirect materials, could go down. Often, explanation of this variance will need clarification from the production supervisor. Another variable overhead variance to consider is the variable overhead efficiency variance.

Determination of Variable Overhead Efficiency Variance

The variable overhead efficiency variance, also known as the controllable variance, is driven by the difference between the actual hours worked and the standard hours expected for the units produced. This variance measures whether the allocation base was efficiently used. The variable overhead efficiency variance is calculated using this formula:

\[\begin{align} \begin{array}{c} \text{Variable Overhead} \\ \text { Efficiency Variance}\\ \end{array} &= \left (\begin{array}{c} \text{Actual Hours Worked } \\ \times\\ \text {Standard Variable Overhead Rate per Hour }\\ \end{array} \right ) - \left (\begin{array}{c} \text{Standard Hours} \\ \times\\ \text {Standard Variable Overhead Rate per Hour}\\ \end{array} \right ) \end{align}\]

Factoring out standard overhead rate, the formula can be written as

\[\begin{align} \begin{array}{c} \text{Variable Overhead} \\ \text {Efficiency Variance}\\ \end{array} &= \left (\begin{array}{c} \text{Actual}\\ \text {Labor Hours } \\ \end{array} - \begin{array}{c} \text{Standard} \\ \text { Labor Hours} \\ \end{array} \right ) \times \begin{array}{c} \text{Standard Overhead} \\ \text {Rate}\\ \end{array} \end{align}\]

If the outcome is favorable (a negative outcome occurs in the calculation), this means the company was more efficient than what it had anticipated for variable overhead. If the outcome is unfavorable (a positive outcome occurs in the calculation), this means the company was less efficient than what it had anticipated for variable overhead.

Connie’s Candy Company wants to determine if its variable overhead efficiency was more or less than anticipated. Connie’s Candy had the following data available in the flexible budget:

Connie’s Candy also had the following actual output information:

To determine the variable overhead efficiency variance, the actual hours worked and the standard hours worked at the production capacity of $100\%$ must be determined. Actual hours worked are $2,500$, and standard hours are $2,000$. The standard variable overhead rate per hour is $\$2.00$ ($\$4,000/2,000$ hours), taken from the flexible budget at $100\%$ capacity. Therefore,

\[\text { Variable Overhead Efficiency Variance }=(2,500-2,000) \times \$ 2.00=\$ 1,000 \text { (Unfavorable) } \nonumber \]

This produces an unfavorable outcome. This could be for many reasons, and the production supervisor would need to determine where the variable cost difference is occurring to make production changes.

Let us look at another example producing a favorable outcome. Connie’s Candy had the following data available in the flexible budget:

Connie’s Candy also had the following actual output information:

Percent of capacity: 100 percent. Direct labor hours 1,800. Units of output 1,000. Variable overhead 3,500. Fixed overhead $6,000. Total overhead $9,500. — Figure $\PageIndex{9}$: Connie’s Candy actual output information

To determine the variable overhead efficiency variance, the actual hours worked and the standard hours worked at the production capacity of $100\%$ must be determined. Actual hours worked are $1,800$, and standard hours are $2,000$. The standard variable overhead rate per hour is $\$2.00$ ($\$4,000/2,000$ hours), taken from the flexible budget at $100\%$ capacity. Therefore,

\[\text { Variable Overhead Efficiency Variance }=(1,800-2,000) \times \$ 2.00=-\$ 400 \text { or } \$ 400 \text { (Favorable) } \nonumber \]

The total variable overhead cost variance is also found by combining the variable overhead rate variance and the variable overhead efficiency variance. By showing the total variable overhead cost variance as the sum of the two components, management can better analyze the two variances and enhance decision-making.

Figure $\PageIndex{10}$ shows the connection between the variable overhead rate variance and variable overhead efficiency variance to total variable overhead cost variance.

There are three top row boxes. Two, Actual Hours (AH) times Actual Rate (AR) and Actual Hours (AH) times Standard Rate (SR) combine to point to a Second row box: Variable Overhead Rate Variance. Two top row boxes: Actual Hours (AH) times Standard Rate (SR) and Standard Hours (SH) times Standard Rate (SR) combine to point to Second row box: Variable Overhead Efficiency Variance. Notice the middle top row box is used for both of the variances. Second row boxes: Variable Overhead Rate Variance and Variable Overhead Efficiency Variance combine to point to bottom row box: Total Variable Overhead Cost Variance. — Figure $\PageIndex{10}$: Variable Overheard Cost Variance. (attribution: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license)

For example, Connie’s Candy Company had the following data available in the flexible budget:

Connie’s Candy also had the following actual output information:

The variable overhead rate variance is calculated as $(1,800 × \$1.94) – (1,800 × \$2.00) = –\$108$, or $\$108$ (favorable). The variable overhead efficiency variance is calculated as $(1,800 × \$2.00) – (2,000 × \$2.00) = –\$400$, or $\$400$ (favorable).

The total variable overhead cost variance is computed as:

\[\text { Total Variable Overhead Cost Variance }=(-\$ 108)+(-\$ 400)=-\$ 508 \text { or } \$ 508 \text { (Favorable) } \nonumber \]

In this case, two elements are contributing to the favorable outcome. Connie’s Candy used fewer direct labor hours and less variable overhead to produce $1,000$ candy boxes (units).

The same calculation is shown as follows in diagram format.

There are three top row boxes. Two, Actual Hours (1,800) times Actual Rate ($1.94) and Actual Hours (1,800) times Standard Rate ($2.00) combine to point to a Second row box: Variable Overhead Rate Variance $108 Favorable. Two top row boxes: Actual Hours (1800) times Standard Rate ($2.00) and Standard Hours (2,000) times Standard Rate ($2.00) combine to point to Second row box: Variable Overhead Efficiency Variance $400 Favorable. Notice the middle top row box is used for both of the variances. Second row boxes: Variable Overhead Rate Variance $108 F and Variable Overhead Efficiency Variance $400 F combine to point to bottom row box: Total Variable Overhead Cost Variance $508 F. — Figure $\PageIndex{12}$: Connie’s Candy Total Variable Overhead Cost Variance calculations

As with the interpretations for the variable overhead rate and efficiency variances, the company would review the individual components contributing to the overall favorable outcome for the total variable overhead cost variance, before making any decisions about production in the future. Other variances companies consider are fixed factory overhead variances.

Fundamentals of Fixed Factory Overhead Variances

The fixed factory overhead variance represents the difference between the actual fixed overhead and the applied fixed overhead. There are two fixed overhead variances. One variance determines if too much or too little was spent on fixed overhead. The other variance computes whether or not actual production was above or below the expected production level.

Example $\PageIndex{1}$: Sweet and Fresh Shampoo Overhead

Biglow Company makes a hair shampoo called Sweet and Fresh. They have the following flexible budget data:

For 90 percent, 100 percent, and 110 percent, respectively: Direct labor hours 14,000, 16,000, 18,000; Units of output 10,000, 10,000, 10,000; Direct labor $525,000, $346,500, $378,000; Variable overhead $315,000, $346,000, $378,000; Fixed overhead $45,500, $45,500, $45,500; Total $953,500, $1,044,300, $1,135,100. — Figure $\PageIndex{13}$: Biglow Company flexible budget data

What is the standard variable overhead rate at $90\%$, $100\%$, and $110\%$ capacity levels?

Solution

$90\% = \$315,000/14,000 = \$22.50$, $100\% = \$346,000/16,000 = \$21.63$ (rounded), $110\% = \$378,000/18,000 = \$21.00$.

THINK IT THROUGH: Purchasing Planes

The XYZ Firm is bidding on a contract for a new plane for the military. As the management team is going over the bid, they come to the conclusion it is too high on a per-plane basis, but they cannot find any costs they feel can be reduced. The information from the military states they will purchase between $50$ and $100$ planes, but will more likely purchase $50$ planes rather than $100$ planes. XYZ’s bid is based on $50$ planes. The controller suggests that they base their bid on $100$ planes. This would spread the fixed costs over more planes and reduce the bid price. The lower bid price will increase substantially the chances of XYZ winning the bid. Should XYZ Firm keep the bid at $50$ planes or increase its bid to $100$ planes? What are the pros and cons to keeping the bid at $50$ or increasing to $100$ planes?

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Creation of Flexible Overhead Budget

Example \(\PageIndex{1}\): Sweet and Fresh Shampoo Overhead

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THINK IT THROUGH: Purchasing Planes