本文旨在研究如何使用边际和吸收成本法编制损益表。吸收成本核算方法收取产品成本的所有直接成本以及间接成本的份额。间接成本使用单一间接费用吸收率计入产品，该费用通过将总成本中心间接费用除以预算生产总量计算得出。（ACCA，2006; Drury，2006; Blocker等，2005）。另一方面，在边际成本计算下，只有可变成本按成本单位计算。固定成本作为期间成本从损益账中扣除。（Drury，2006; Blocker等，2005）。下面的a）和b）部分分别显示了在2006年和2007年结束的年份中生产和销售单一产品的H有限公司的边际和吸收成本收益表。假设公司使用先进先出（FIFO）方法来估算库存。此外，假设公司每年根据预算单位和实际单位采用单一的管理费吸收率，两年的预算单位完全相等。
This paper aims to look at how income statements are prepared using marginal and absorption costing. The absorption costing method charges all direct costs to the product costs, as well as a share of indirect costs. The indirect costs are charged to products using a single overhead absorption rate, which is calculated by dividing the total cost centre overhead to the total volume of budgeted production. (ACCA, 2006; Drury, 2006; Blocker et al., 2005). On the other hand under marginal costing, only variable costs are charged to cost units. Fixed costs are written off the profit and loss account as period costs. (Drury, 2006; Blocker et al., 2005). Sections a) and b) below show the marginal and absorption costing income statements respectively for H Ltd that manufactures and sells a single product during the years ending 2006 and 2007. It is assumed that the company uses the first-in-first-out (FIFO) method for valuing inventories. In addition it is assumed that the company employs a single overhead absorption rate each year based on budgeted units and actual units exactly equalled budgeted units for both years.
|H Ltd Income Statement (Marginal Costing)||2006||2007|
|Cost of Sales:|
|Production cost (W1, W2)||700||500|
|Variable Marketing and Admin||1000||1200|
|Cost of Goods available for sale||1700||2100|
|Ending inventory (W3, W4)||200||100|
|Less Fixed costs|
|Marketing and Admin||400||400|
|H Ltd Income Statement (Absorption Costing)||2006||2007|
|Cost of Sales|
|Production Cost (W5, W6)||1400||1200|
|Ending Inventory (W7, W8)||400||240|
|Marketing and Admin Expenses|
Reconciliation of net income under absorption and Marginal Costing.
|Absorption operating profit||600||640|
|Less Fixed overhead cost in ending inventory (W9)||200||140|
|Marginal Costing net income||400||500|
Under marginal costing inventory of finished goods as well as work in progress is valued at variable costs only. On the contrary, absorption costing values stocks of inventory of finished goods and work in progress at both variable costs and an absorbed amount for fixed production overheads. (ACCA, 2006; Lucy, 2002). In the case of H Ltd, under marginal costing, only variable costs are included in the ending inventory figure. This results in a profit figure of £400,000. On the other hand absorption costing includes additional £200,000 as fixed overhead in the ending inventory for 2006. As a result absorption operating profit is overstated by £200,000 in 2006. In like manner, the absorption profit under absorption costing is overstated by £140,000 due to an inclusion of £140,000 of fixed overhead cost in the ending inventory figure for 2007. To reconcile the profit under absorption costing and marginal costing, we may either subtract the fixed overhead included in ending inventory from the absorption cost operating profit to arrive at the marginal cost operating profit or add the fixed overhead costs in ending inventory to the marginal cost operating profit to arrive at the absorption cost operating profit.
Stock build-ups may result from using absorption costing for performance measurement purposes because inventory is valued at both fixed and variable costs. Firstly, profit is overstated. In fact absorption costing enables income manipulation because when inventory increases fixed costs in the current year can be deferred to latter years and as such current net income is overstated which in effect results in financial statements that do not present fairly and as such affect users’ decisions on the financial statements. Secondly, maintaining high levels of inventory may result in obsolescence and as such declines in future profitability resulting from the loss in value of the inventory. (Blocher et al., 2005; Storey, 2002).
Advantages of Absorption Costing and Marginal Costing
According to ACCA (2006) the following arguments have been advanced for using absorption costing:
- It is necessary to include fixed overhead in stock values for financial statements. This is because routine cost accounting using absorption costing produces stock values which include a share of fixed overhead. Based on this argument, financial statements prepared using absorption costing present a true and faithful representation of the actual results of operation of the company.
- For a small jobbing business, overhead allotment is the only practicable way of obtaining job costs for estimating and profit analysis.
- Analysis of under/over-absorbed overhead is useful to identify inefficient utilisation of production resources.
ACCA (2006) also identifies a number of arguments in favour of marginal costing. Preparation of routine cost accounting statements using marginal costing is considered more informative to management for the following reasons:
- Contribution per unit represents a direct measure of how profit and volume relate. Profit per unit is a misleading figure.
- Build-up or run-down of stocks of finished goods will distort comparison of operating profit statements. In the case of closing inventory, the inventory is valued only at the variable cost per unit. This makes the profit under a situation where there is closing inventory to be the same as the case when there is no closing inventory thereby enabling the comparison of operating profit statements over time.
- Unlike under absorption costing, marginal costing avoids the arbitrary apportionment of fixed costs, which in turn result in misleading product cost comparisons.
- ACCA (2006). Paper 2.4 Financial Management and Control: Study Text 2006/2007. www.kaplanfoulslynch.com
- Blocher, E., Chen, K., Cokins, G., Lin, T. (2005). Cost Management A Strategic Emphasis. 3rd Edition McGraw Hill.
- Drury, C. (2004). Management and Cost Accounting. 6th Edition. Thomson Learning, London.
- Lucy, T (2002), Costing, 6th ed., Continuum.
- Storey, P (2002), Introduction to Cost and Management Accounting, Palgrave Macmillan