存貨成本核算適用性研究：以某電子製造公司為例

台灣的電子製造業為國際品牌設計或代工居多，客戶常以各種方式不斷地要求代工廠降低成本與準時交貨，在如此微利的全球競爭環境下，惟有適當與精確的成本核算方法，才能使資源做有效的配置，與競爭對手產生差異化，進而創造企業價值。個案公司是知名的數位液晶顯示器代工廠，設計與代工之機種繁多，舉凡世界前五大PC廠均為其客戶，每月出貨數量高達百萬台，金額約新台幣60至80億。然營業額雖高，但產品毛利低，在成本的管控上相對較其他電子業更為嚴峻，再者，直接材料成本中的關鍵零組件，液晶面板佔總成本高達八至九成，長期迫於市場供需不穩之問題，面板交易的價格每月波動且難以預測，對採用標準成本制的個案公司產生巨額有利或不利之標準差異，不僅僅加重財會人員的帳務處理負擔，亦無法突顯標準成本制的優點。如果與客戶之交易模式為出廠交貨(Ex-work)或船邊交貨(FOB)，購、產、銷發生在同月，所產生之標準差異即當期認列，帳務作業雖然繁複，不致於造成成本錯誤，但交易模式為即時供貨(JIT)或供應商代管存貨(VMI)時，跨洲際的運輸及安全庫存的要求，使得存貨週轉日長達數月，所累積換算的標準差異，不僅是金額甚鉅，若是採當期認列並以存銷比法分攤差異，將導致存、銷貨成本偏離實際成本。事實上，置身買方市場的氛圍，個案公司約八成以上之客戶均採用供應商代管存貨(VMI)模式進行交易。基於稅法與會計制度均要求以實際成本反應存貨與銷貨成本，十號公報亦載明標準成本應考量原物料、人工、效率與設備產能之正常水平，定期複核並於必要時配合現狀調整，經過個案公司中不同事業部的比較驗證，本論文建議中、大型企業，若使用標準成本制、產品中有高單價且價格波動劇烈的零組件及以JIT或VMI之模式交易，應採用Batch(連結)取代存銷比的成本核算方法，藉由資訊系統的演算協助，連結工單甚至於零組件訂單(PO)的價格，追溯並精確分攤不利/利差，正確計算銷、存貨成本與損益；後續可期進一步研究與客戶報價公式整合，以建立整套更具攸關性的成本計算機制。

關鍵字

關鍵零組件；即時供貨；供應商代管存貨；標準差異

並列摘要

The electronics manufacturing industry in Taiwan are mostly OEM and ODM for international brands all the time. Customers keep requesting cost reduction and accurate deliveries in various ways. Under such environment of low margin and global competition, only the appropriate and accurate costing method can reallocate resources efficiently to differentiate with competitors and then create business value. The subject company is well-known digital LCD display foundries to serve clients of the world’s top five PC makers by production of numerous models with shipments of one million units and 6 to 8billions NT dollars per month. More strictly management on cost control compared to other industry based on the business of high revenue but low margin. However, the key component, LCD panel which belongs to the direct materials takes nearly 90% of total cost, forced by volatile supply and demand of market, panel price fluctuated monthly and very difficult to predict. Therefore, lead the subject company who uses standard cost system produces a lots of favorable or unfavorable variance which increasing the burden on accountants to calculate costs, also unable to outstand the advantages of the standard cost system. Furthermore, if the business model with customer is Ex-work or FOB，the standard variances could be recognized in the current, it won’t result in costs error although heavier accounting works. Otherwise, the inventory turnover days of JIT or VMI models is several months by long transportation of cross continentals and requirement of safety stock and that cumulative variances not only huge but also away from the actual cost if recognized in the current or shared by sales to inventory ratio. In fact, as the environment of buy side, about 80% clients of the subject company apply the model of VMI. Based on the tax laws and accounting system requires to use actual cost to reflect inventory and cost of goods sold, the No. 10 statement of accounting standards requests that the standard cost should consider the normal level of raw materials, labor, efficiency and equipment capacity to review regularly and adjust by current situation if necessary. After comparison and validation by different business units of subject company, this thesis proposes to use the costing method of batch linking to replace inventory to sales ratio for large-scale enterprises which use standard cost system, has critical components of high and volatile unit price and take models of JIT or VMI. Through assistance of IT system to link work orders even to component Pos, it can track and share positive and negative variance correctly to calculate cost of inventory , sales and produce P&L reports. Furthermore, to research the combination with customer quotation formula so that establish a complete and more relevant costing mechanism.