The Effect of Work in Process Inventories on Process Costing

Process costingbecomes more complicated when there are both beginning and ending work in process (BWIP and EWIP) inventories. The costs stored in BWIP were incurred during the prior period. A decision must be made about how to handle those costs.

There are two methods for treating BWIP costs when computing the unit cost for the current period: the weighted average costing method and the FIFO costing method. The primary difference between the two methods is in the calculation of cost per equivalent unitspecifically, what costs are included in the numerator and what units are included in the denominator.

Under theweighted average method, the costs in BWIP are treated as though they are part of the manufacturing costs for the current period. Therefore, the BWIP costs are added to the manufacturing costs for the current period to determine the numerator for the cost per equivalent unit. The number of units in BWIP is also assumed to be started and completed during the current period. The denominator has three parts:

1. Actual number of units in BWIP (100%)
2. Actual number of units started and completed during the period
3. Equivalent units for the work on EWIP

Under theFIFO method, BWIP costs are not included in the calculation of cost per equivalent unit. Only the manufacturing costs incurred during the current period are used as the numerator. The FIFO method assumes that the units in BWIP are completed first and are measured as equivalent units (contrary to the weighted average method, which counts BWIP units at 100%). Thus, the denominator has three parts:

1. Equivalent units for the work to be completed on BWIP
2. Actual number of units started and completed during the period
3. Equivalent units for the work on EWIP

Answer the following:

Select the costing method that includes costs for beginning work in process in the calculation of cost per equivalent unit.selectFIFOWeighted averageCorrect 1 of Item 1

Select the costing method that counts units for the completion of the beginning work in process as equivalent units.selectFIFOWeighted averageCorrect 2 of Item 1

Because the first-in, first-out (FIFO) method is often the same as the physical flow of units, most companies use the FIFO method. Regardless of the method used, there are five steps in process costing calculations. These calculations allocate costs to inventories at the end of each period.

Step 1: Analyze the Physical Flow The purpose of this step is to provide a summary of all units for which some work had been done during the period. This step is the same for both costing methods. Basically, this step accounts for the BWIP and the units started. This step determines if those units arecompleted(and transferred out) or in EWIP. The key is that these must be equal. Complete the following formula to illustrate this relationship:

BWIP

+

selectUnits StartedUnits CompletedCorrect 1 of Item 2

=

selectUnits StartedUnits CompletedCorrect 2 of Item 2

+

EWIP

APPLY THE CONCEPTS: Step 1

Analyze the physical flow for In the Doghouse In the Doghouse produces wooden doghouses with shingled roofs. At the beginning of July, there were 200 units in BWIP with costs of $9,576. During the month, the company completed work on the BWIP and began production on 1,000 units. In the Doghouse incurred $79,980 in manufacturing costs during July. At the end of the month, 300 units of those started during the month were in EWIP. In the table to the below, account for the units for July.

Physical flow for July
Completed from BWIP
Started and completed
	Total units completed
EWIP
	Total units accounted for

Step 2: Calculate the Equivalent Units for the Period The units in BWIP and EWIP are not 100% complete. This step allows BWIP and EWIP to be stated in terms of completed units, which are calledequivalent units. This step must be completed before the cost per unit can be calculated.

Under theweighted average method, BWIP is considered to be started and completed during the period when calculating equivalent units. Therefore, BWIP units are included at 100%. Under theFIFO method, the BWIP units are measured by the percentage of work required to complete those units. Therefore, the percentage of work that needs to be done to complete the units must be multiplied by the number of units in BWIP.

APPLY THE CONCEPTS: Step 2 Using the data from above, calculate the Equivalent Units for July. (Note: In the Doghouses production manager has estimated that the units in BWIP were 80% complete at the beginning of July. The BWIP units were completed during the month. That is, 20% of the work to complete the units was done in the current period (100% 80% = 20%). The manager has also estimated that EWIP was 40% complete at the end of month. Refer to the analysis of the physical flow.)

Equivalent units for July	Weighted average	FIFO
BWIP
Units started and completed
EWIP
July equivalent units

Step 3: Compute the Cost per Equivalent Unit

The calculation for cost per equivalent unit is a simple calculation:

Manufacturing Costs

Equivalent Units

Under the weighted average method, the numerator is the sum of the manufacturing costs in BWIP and the manufacturing costs for the period. Under the FIFO method, the beginning inventory costs are excluded from this calculation. The numerator is the manufacturing costs for the current period only. Equivalent units for the period were computed in step 2.

APPLY THE CONCEPTS: Step 3 Recall that the BWIP had costs of $9,576. During July, In the Doghouse incurred $79,980 in manufacturing costs. Complete the formula and cost per equivalent unit for the weighted average method and for the FIFO method to the below. If required, round the cost per equivalent unit amount to the nearest cent.

Compute the Weighted Average Cost per Equivalent Unit for July

Weighted Average Cost per Equivalent Unit =	$
=	$

Compute the FIFO Cost per Equivalent Unit for July

FIFO Cost per Equivalent Unit =
=	$

Step 4: Valuation of Inventories In this step, the cost of the units transferred out of the current process to Finished Goods is computed by using the information calculated in steps 2 and 3.

Recall that the weighted average method assumes that BWIP units are started and completed during the current period. Because of this assumption, BWIP costs were included in the cost per equivalent unit. Therefore, costs transferred out (to Finished Goods) are calculated by multiplying the units started and completed (step 2) times the weighted average cost per equivalent unit (step 3).

The FIFO method requires the BWIP equivalent units to be added to the units started and completed to determine the units transferred out (step 2). These units are multiplied times the FIFO cost per equivalent unit (step 3). This amount is added to the costs in BWIP to determine the costs transferred out (to Finished Goods). If required, round the cost per equivalent unit amounts to the nearest cent.

APPLY THE CONCEPTS: Step 4

Valuation of Inventories for July

Inventory Valuation for July	Weighted average	FIFO
Finished Goods:
BWIP equivalent units
Started and completed
Units transferred out
x Cost per equivalent unit	$		$
$		$
+ BWIP costs
Costs transferred out	$		$
EWIP:
EWIP equivalent units
x Cost per equivalent unit	$		$
Costs in EWIP	$		$

Step 5: Cost Reconciliation The purpose of cost reconciliation is to confirm that costs have been fully allocated to inventories. The total costs to account for are the sum of the costs in BWIP and the manufacturing costs for the period. This sum is reconciled by showing that it has been allocated to Finished Goods (units transferred out) and EWIP.

APPLY THE CONCEPTS: Step 5 Cost Reconciliation for July

Weighted average	FIFO
Costs to account for:
Costs in BWIP	$	$
Manufacturing costs during July
	Total costs to account for	$	$
Cost reconciliation:
Costs transferred out	$	$
Costs in EWIP
	Total costs accounted for	$	$