第六章 作業成本制
（Activity-Based Costing ; ABC）
(李 -723)
先將製造費用歸屬於每一作業，再由每一作業分攤於
產品。其係採用多項〞產量有關〞與〞產量無關〞之
作業動因（ Cost Driver）
• 實施步驟：
– 選擇同質之成本庫與其成本動因：
• 同質之成本庫係指可用一項共同之作業動因解釋其成本
變動之製造費用
– 計算每一成本庫之分攤率（pool rate）：即每一成
本庫每單位作業動因之成本
• 成本庫分攤率＝(預估成本庫各製造費用總額／預估作業
動因總耗用量）
– 以成本庫分攤率將成本庫製造費用分攤於產品
• 分攤之製造費用＝成本庫分攤率＊作業動因耗用之單位
作業成本制 (李pp711-723)
以圖表20-1、圖表20-3之資料為例；將整備與檢驗成本歸為第一成本庫
（以整備次數為作業動因），將電費與維護歸為第二成本庫（以機器小時
為作業動因）。
第一階段：計算成本庫分攤率
第一成本庫：以整備次數為作業動因 第二成本庫：以機器小時為作業動因
整備成本 $80,000 電費 $72,000
檢驗成本 70,000 維護費 78,000
合計 $150,000 合計 $150,000
第二成本庫分攤率＝＄150,000÷60,000＝ ＄
第一成本庫分攤率＝＄150,000÷50,000＝＄ 3,000
作業成本制
第二階段：將成本庫之製造費用分攤於產品
作業成本制
作業動因之選擇：考慮(1)衡量成本(2)作業動因與實際製造
費用之關係
作業成本制
作業成本制
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Shifting of Overhead Cost
• When a company installs an activity-based costing system,
overhead cost is often shifted from the high-volume products to
the low-volume products, with a higher unit cost resulting for
the low-volume products
• First, rather than treating overhead cost as a lump amount and
spreading it uniformly over all products, activity-based costing
attempts to more accurately assign costs to specific products.
Since low-volume products often require special equipment,
special handling, and so forth, they typically are responsible for
the incurrence of a disproportionately large amount of overhead
cost
• Second, many overhead costs are incurred at the batch level.
Since low-volume products typically have fewer units processed
per batch than high-volume products, their average processing
cost per unit is higher. For example, consider the cost of issuing
production orders, which is a batch activity, for Comtek Sound,
Inc. As show in Exhibit 5-6, the average cost to Comtek Sound
to issue a single production order is $375. However, fewer CD
units(the low-volume product) are processed per production
order than tape units
Shifting of Overhead Cost
CD Units Tape Units
Number of units produced per year(a)…………………… 50,000 200,000
Number of production orders issued per year(b)………… 400 800
Number of units processed per production order(a)/(b) 125 250
If we now spread the $375 cost to issue a production order over the
number of units processed per order we get the following:
CD Units Tape Units
Cost to issue a production order(a)…………………… $375 $375
Number of units processed per production order(above)(b) 125 250
Production order cost per unit(a)/(b) $ $
Thus, the production order cost for a CD unit (the low-volume product)is
$3, which is double the $ cost for a tape unit
Cost Flow under Activity-Based Costing
