Question

Explain the basic ideas underlying process costing and how they differ from job costing. Demonstrate how the presence of beginning inventories affects the computation of unit costs under the first in, first out method.

Answer 1

PROCESS COSTING

Process costing is used when there is mass production of similar products, where the costs associated with individual units of output cannot be differentiated from each other. In other words, the cost of each product produced is assumed to be the same as the cost of every other product. Under this concept, costs are accumulated over a fixed period of time, summarized, and then allocated to all of the units produced during that period of time on a consistent basis.

For example, oil refining, food production, and chemical processing.

Types of Process Costing

There are three types of process costing, which are:

Weighted average costs : This version all costs, whether from a preceding period or the current one, are lumped together and assigned to produced units. It is the simplest version to calculate.

Standard costs : This version is based on standard costs. Its calculation is similar to weighted average costing, but standard costs are assigned to production units, rather than actual costs; after total costs are accumulated based on standard costs, these totals are compared to actual accumulated costs, and the difference is charged to a variance account.

First-in first-out costing (FIFO) : FIFO is a more complex calculation that creates layers of costs, one for any units of production that were started in the previous production period but not completed, and another layer for any production that is started in the current period.

Significant differences of Job costing and process costing systems.

5. Types of products produced. Companies that use job costing work on many different jobs with different production requirements during each period. Companies that use process costing produce a single product, either on a continuous basis or for long periods. All the products that the company produces under process costing are the same.

5. Cost accumulation procedures. Job costing accumulates costs by individual jobs. Process costing accumulates costs by process or department.

5. Work in Process Inventory accounts. Job cost systems have one Work in Process Inventory account for each job. Process cost systems have a Work in Process Inventory account for each department or process.

FIFO costing method separates work and costs of the equivalent units in beginning inventory from work and costs of the equivalent units produced during the current period.

• • Only current work and costs are used to calculate this period’s unit cost.
  • It is assumed that units from beginning inventory are completed first and transferred out.
  • The costs of these units include the costs of the work done in the prior period as well as the current period costs necessary to complete the units.
• Units started in the current period are divided into two categories:
  • units started and completed and
  • units started but not finished (EWIP).
• Units in both of these categories are valued using the current period’s cost per equivalent unit.

DEMONSTRATION (FIFO Method)

We use an example of the month of June production costs for a company’s Department B. Department B adds materials only at the beginning of processing. The May 31 inventory in Department B (June’s beginning work in process) consists of 2,000 units that are fully complete as to materials and 60% complete as to conversion. Beginning work in process inventory has accumulated costs of $6,180.

The following costs were added in June: Direct materials issued $ 1,300; direct labor $ 7,200; and manufacturing overhead applied $ 6,000. The units for the period were:

Beginning work in process inventory	2,000 units
Units started this period	10,000 units
Ending work in process inventory	3,000 units

Ending work in process inventory was 1/3 complete as to conversion costs.

Step 1: Physical Flow of Units

For the physical flow of units, we calculate units started AND completed this period as Units started 10,000 – units remaining in ending work in process 3,000 = 7,000 units.

Units in Beg. WIP	2,000	Units Completed and Transferred:
Units Started this period	10,000	Units from Beg. WIP	2,000
Total Units	12,000	Units started and completed	7,000	(10,000 – 3,000)
		Total Units completed and txfr		9,000
		Units in End. WIP		3,000
		Total Units		12,000

Step 2: Equivalent Units of Production

We are concerned with the right side of our physical flow of units. We must first FINISH beginning work in process, add units started and completed and units remaining in ending work in process. Beginning work in process is fully complete for materials (or 100% complete) and 60% complete for conversion so to complete these units we will need NO (or 0%) materials and 40% of conversion (100% – 60%). Units started and completed are always 100% complete for materials, labor and overhead! Ending work in process is 1/3 complete for conversion costs, but what about materials? The problem information reads “Department B adds materials only at the beginning of processing” which means we receive all (or 100%) of the materials at the beginning of the process and ending work in process will be fully complete for materials.

	Materials	Conversion Costs
Units from beginning WIP	0	800
	[ 2,000 units x (100% – 100% complete)]	[ 2,000 units x (100% – 60% complete)]
Units started and completed	7,000	7,000
	(7,000 units x 100% complete)
Units in ending WIP	3,000	1,000
	(3,000 units x 100% complete)	(3,000 units x 1/3 complete)
Total Equivalent Units	10,000	8,800

Step 3: Cost per Equivalent Units

Under FIFO, we are only interested in the current period costs which is June for this example. Conversion costs are direct labor $7,200 + overhead $6,000.

	Materials	Conversion Costs
Current Costs added this period	$   1,300	$   13,200	(7,200 + 6,000)
÷ Total Equivalent Units	10,000	8,800
= Cost per Equivalent Unit	$     0.13	$      1.50

Step 4: Assign Costs to Units Completed and Ending Work in Process Inventory

Under FIFO, remember to bring over the costs of beginning work in process first, then multiply the individual equivalent units calculated in step 2 (not the total equivalent units) by the cost per equivalent unit from step 3.

Cost assigned to units completed and transferred out:
Cost of beginning work in process inventory		$6,180
Cost to complete beginning work in process inventory
Materials (0 equivalent units)	$0
Conversion   (800 equiv units x $1.50)	$1,200
		$1,200
Cost of units started and completed
Materials (7,000 equiv units x $0.13)	$910
Conversion   (7,000 equiv units x $1.50)	$10,500
		$11,410
Total cost of units completed and transferred		$18,790
Cost assigned to ending work in process inventory:
Materials (3,000 equiv units x $0.13)	$390
Conversion   (1,000 equiv units x $1.50)	$1,500
Total cost of units remaining in ending work in process inventory		$1,890

Step 5: Reconcile Costs

Here is our chance to check our work. Total costs to account for should always equal what was assigned in total costs accounted for.

Cost of beginning work in process	$6,180
Costs added in June	$14,500	(1,300 DM + 7,200 DL + 6,000 OH)
Total costs to account for	$20,680
Costs assigned to units completed	$18,790	(from step 4 above)
Costs assigned to ending work in process	$1,890	(from step 4 above)
Total costs accounted for	$20,680