Costing can be defined as the technique and process of ascertaining costs. The principles in every method of costing are same but the methods of analyzing and presenting the costs differ with the nature of business. The methods of job costing are as follows:
1. Job Costing
The system of job costing is used where production is not highly repetitive and in addition consists of distinct jobs so that the material and labor costs can be identified by order number. This method of costing is very common in commercial foundries and drop forging shops and in plants making specialized industrial equipments. In all these cases, an account is opened for each job and all appropriate expenditure is charged thereto.
2. Contract Costing
Contract costing does not in principle differ from job costing. A contract is a big job whereas a job is a small contract. The term is usually applied where large-scale contracts are carried out. In case of ship-builders, printers, building contractors etc., this system of costing is used. Job or contract is also termed as terminal costing.
3. Cost Plus Costing
In contracts where in addition to cost, an agreed sum or percentage to cover overheads and fit is paid to a contractor, the system is termed as cost plus costing. The term cost here includes materials, labor and expenses incurred directly in the process of production. The system is used generally in cases where government happens to be the party to give contract.
4. Batch Costing
This method is employed where orders or jobs are arranged in different batches after taking into account the convenience of producing articles. The unit of cost is a batch or a group of identical products instead of a single job order or contract. This method is particularly suitable for general engineering factories which produce components in convenient economic batches and pharmaceutical industries.
5. Process Costing
If a product passes through different stages, each distinct and well defined, it is desired to know the cost of production at each stage. In order to ascertain the same, process costing is employed under which a separate account is opened for each process.
This system of costing is suitable for the extractive industries, e.g., chemical manufacture, paints, foods, explosives, soap making etc.
6. Operation Costing
Operation costing is a further refinement of process costing. The system is employed in the industries of the following types:
a. The industry in which mass or repetitive production is carried out
b. The industry in which articles or components have to be stocked in semi-finished stage to facilitate the execution of special orders, or for the convenience of issue for later operations
The procedure of costing is broadly the same as process costing except that in this case, cost unit is an operation instead of a process. For example, the manufacturing of handles for bicycles involves a number of operations such as those of cutting steel sheets into proper strips molding, machining and finally polishing. The cost to complete these operations may be found out separately.
7. Unit Costing (Output Costing or Single Costing)
In this method, cost per unit of output or production is ascertained and the amount of each element constituting such cost is determined. In case where the products can be expressed in identical quantitative units and where manufacture is continuous, this type of costing is applied. Cost statements or cost sheets are prepared in which various items of expense are classified and the total expenditure is divided by the total quantity produced in order to arrive at per unit cost of production. The method is suitable in industries like brick making, collieries, flour mills, paper mills, cement manufacturing etc.
8. Operating Costing
This system is employed where expenses are incurred for provision of services such as those tendered by bus companies, electricity companies, or railway companies. The total expenses regarding operation are divided by the appropriate units (e.g., in case of bus company, total number of passenger/kms.) and cost per unit of service is calculated.
9. Departmental Costing
The ascertainment of the cost of output of each department separately is the objective of departmental costing. In case where a factory is divided into a number of departments, this method is adopted.
10. Multiple Costing (Composite Costing)
Under this system, the costs of different sections of production are combined after finding out the cost of each and every part manufactured. The system of ascertaining cost in this way is applicable where a product comprises many assailable parts, e.g., motor cars, engines or machine tools, typewrite$, radios, cycles etc.
As various components differ from each other in a variety of ways such as price, materials used and manufacturing processes, a separate method of costing is employed in respect of each component. The type of costing where more than one method of costing is employed is called multiple costing.
It is to be noted that basically there are only two methods of costing viz. job costing and process costing. Job costing is employed in cases where expenses are traceable to specific jobs or orders, e.g., house building, ship building etc. In case where it is impossible to trace the prime cost of the items for a particular order because of the reason that their identity gets lost while manufacturing operations, process costing is used. For example, in a refinery where several tons of oil is being produced at the same time, the prime cost of a specific order of 10 tons cannot be traced. The cost can be found out only by finding out the cost per ton of total oil produced and then multiplying it by ten.
It may, therefore, be concluded that the methods of batch contract and cost plus costing are only the variants of job costing whereas the methods of unit, operation and operating costing are the variants of process costing.