Time-Driven Activity-Based Costing
Robert S. KaplanSteven R. Anderson
From the November 2004 Issue
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In the classroom, activity-based costing looks like a great way to manage a company’s limited resources. But many managers who have tried to implement ABC in their organizations on any significant scale have abandoned the attempt in the face of rising costs and employee irritation. They should try again, because the new approach we lay out in the following pages sidesteps the difficulties traditionally associated with large-scale ABC implementation by relying on informed managerial estimates rather than on employee surveys. It also provides managers with a far more flexible cost model to capture the complexity of their operations.
ABC Made Difficult
The roots of the problem with ABC lie in the way people traditionally construct ABC models. Assume you are analyzing a customer service department that performs three activities: processing orders, handling inquiries, and performing credit checks. The department’s total expenses (the cost of the personnel, management, IT, telecommunications, and other fixed resources) amount to $560,000. The actual (or estimated) quarterly quantities of work in the three activities are 49,000 orders, 1,400 inquiries, and 2,500 credit checks.
To build a traditional ABC model for this department, you would survey employees to estimate the percentage of time they spend (or expect to spend) on the three activities and then assign the department’s resource expenses according to the average percentages you get from the survey. Let’s say employees report that they spend (or expect to spend) about 70% of their time on customer orders, 10% on inquiries or complaints, and 20% on credit checks. This implies, under ABC, that each order consumes $8 of resource expense, each inquiry $40, and each credit check $44.80, as shown in the exhibit “Doing ABC the Traditional Way.” Armed with these figures, known as the cost-driver rates, managers can assign the costs of the department’s resources to the customers and products that use its services.
Doing ABC the Traditional Way
This approach works well in the limited setting in which it was initially applied, typically a single department, plant, or location. Difficulties arise, however, when you try to roll this approach out on a large scale for use on an ongoing basis. In one large bank’s brokerage operation, the ABC data-gathering process required 70,000 employees at more than 100 facilities to submit monthly reports of their time allocation. The company employed 14 people full-time just to manage the data collection, processing, and reporting.
The time and cost demands of creating and maintaining an ABC model on this scale is a major barrier to widespread adoption at most companies. Since the systems that are put in place are updated infrequently (because of the costs of reinterviewing and resurveying), the model’s estimates of process, product, and customer costs soon become inaccurate. What’s more, people waste their time arguing about the accuracy of cost-driver rates that are derived from individuals’ subjective beliefs rather than addressing the deficiencies the model reveals: inefficient processes, unprofitable products and customers, and excess capacity.
Traditional ABC models also often fail to capture the complexity of actual operations. Consider the activity “ship order to customer.” Rather than assume a constant cost per order shipped, a company may wish to recognize the cost differences when an order is shipped in a full truck, in a less-than-truckload (LTL) shipment, using overnight express, or by a commercial carrier. In addition, the order may be entered into the system either manually or electronically, and it may be either a standard or an expedited transaction. To allow for the significant variation in resources required by the different shipping arrangements, new activities must be added to the model, thereby expanding its complexity.
As the activity dictionary expands—either to reflect more detail about activities or to expand the scope of the model to the entire enterprise—the demands on the computer programs used to store and process the data escalate. Suppose a company has 150 activities in its enterprise ABC model, applies the costs in these activities to some 600,000 cost objects (products and customers), and runs the model monthly for two years. That would require data estimates, calculations, and storage for more than 2 billion items.
Such expansion has caused ABC systems to exceed the capacity of generic spreadsheet tools, such as Microsoft Excel, and even many ABC software packages. The systems could take days to process one month’s worth of data. For example, the automated ABC model for Hendee Enterprises, a $12 million fabricator of awnings, took three days to calculate costs for its 40 departments, 150 activities, 10,000 orders, and 45,000 line items.
These problems have become obvious to most ABC implementers. But a subtle and more serious problem arises from the interview and survey process itself. When people estimate how much time they spend on a list of activities handed to them, they invariably report percentages that add up to 100. Few individuals report that a significant percentage of their time is idle or unused. Therefore, cost-driver rates are calculated assuming that resources are working at full capacity. But as we all know, operations often run at considerably less than their capacity. That means that the estimated cost-driver rates are usually much too high. (Technically, they will be overstated by the reciprocal of the capacity utilization percentage: At 80% utilization, the rates are 25% too high; at 67% utilization, the rates are 50% too high.)
The New ABC
The solution to the problems with ABC is not to abandon the concept. ABC after all has helped many companies identify important cost- and profit-enhancement opportunities through the repricing of unprofitable customer relationships, process improvements on the shop floor, lower-cost product designs, and rationalized product variety. Its potential on a larger scale represents a huge opportunity for companies. Fortunately, simplification is now possible through an approach that we call time-driven ABC, which we have successfully helped more than 100 client companies implement, including those described in this article. In the revised approach, managers directly estimate the resource demands imposed by each transaction, product, or customer rather than assign resource costs first to activities and then to products or customers. For each group of resources, estimates of only two parameters are required: the cost per time unit of supplying resource capacity and the unit times of consumption of resource capacity by products, services, and customers. At the same time, the new approach provides more accurate cost-driver rates by allowing unit times to be estimated even for complex, specialized transactions.
In the revised approach, managers directly estimate the resource demands imposed by each transaction, product, or customer.
Estimating the cost per time unit of capacity.
Instead of surveying employees on how they spend their time, managers first directly estimate the practical capacity of the resources supplied as a percentage of the theoretical capacity. There are various ways to do this. As a rule of thumb, you could simply assume that practical full capacity is 80% to 85% of theoretical full capacity. So if an employee or machine is available to work 40 hours per week, its practical full capacity is 32 to 35 hours per week. Typically, managers would allot a lower rate—say 80%—to people, allowing 20% of their time for breaks, arrival and departure, communication, and training. For machines, managers might allot a 15% differential between theoretical and practical capacity to allow for downtime due to maintenance, repair, and scheduling fluctuations. A more systematic approach, perhaps, is to review past activity levels and identify the month with the largest number of orders handled without excessive delays, poor quality, overtime, or stressed employees. Whichever approach you prefer, it’s important not to be overly sensitive to small errors. The objective is to be approximately right, say within 5% to 10% of the actual number, rather than precise. If the estimate of practical capacity is grossly in error, the process of running the time-driven ABC system will reveal the error over time.
Returning to our example, let’s assume that the customer service department employs 28 reps to do the frontline work and that each puts in eight hours per day. In theory, therefore, each worker supplies about 10,560 minutes per month or 31,680 minutes per quarter. The practical capacity at about 80% of theoretical is therefore about 25,000 minutes per quarter per employee, or 700,000 minutes in total. Since we already know the cost of supplying capacity—the $560,000 in overhead costs—we can now calculate the cost per minute of supplying capacity ($0.80).
The capacity of most resources is measured in terms of time availability, but the new ABC approach can also recognize resources whose capacity is measured in other units. For example, the capacity of a warehouse or vehicle would be measured by space provided, while memory storage would be measured by megabytes supplied. In these situations, the manager would calculate the resource cost per unit based on the appropriate capacity measure, such as cost per cubic meter or cost per megabyte.
Estimating the unit times of activities.
Having calculated the cost per time unit of supplying resources to the business’s activities, managers next determine the time it take
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تقدير التكاليف يحركها وقت على أساس النشاطروبرت س. كابلانستيفين ر. أندرسون من هذه المسألة في تشرين الثاني/نوفمبر 2004ملخصحفظحصةالتعليقحجم النصطباعة 8.95شراء نسخ عرض المزيد منالقضية في تشرين الثاني/نوفمبر 2004بحث في الأرشيفتحميل...في الفصول الدراسية، وتبدو التكاليف على أساس النشاط مثل طريقة رائعة لإدارة الموارد المحدودة للشركة. ولكن العديد من المديرين الذين حاولوا تنفيذ ABC في منظماتهم بأي مقياس كبير قد تخلت عن المحاولة مواجهة التكاليف المتزايدة وتهيّج الموظف. أنها ينبغي أن المحاولة مرة أخرى، لأن النهج الجديد علينا وضع في الصفحات التالية الالتفاف الصعوبات المرتبطة تقليديا بتنفيذ أية بي سي على نطاق واسع بالاعتماد على تقديرات إدارية مستنيرة بدلاً من الدراسات الاستقصائية للموظف. كما توفر للمديرين مع نموذج تكلفة الآن أكثر مرونة لالتقاط الطابع المعقد لعملياتها.أي بي سي من صعوبةتكمن جذور المشكلة مع أية بي سي في الطريق الناس عادة بناء نماذج ABC. تفترض كنت تقوم بتحليل قسم خدمة العملاء الذي يقوم بأنشطة ثلاثة: تجهيز الطلبات والتعامل مع الاستفسارات وأداء الائتمان الشيكات. النفقات الإجمالية للإدارة (تكاليف الموظفين والإدارة وأنها، الاتصالات السلكية واللاسلكية والموارد الثابتة الأخرى) مبلغ 560,000 دولار. الكميات الفصلية الفعلية (أو المقدر) للعمل في الأنشطة الثلاثة هي أوامر 49,000 والاستفسارات 1,400 2,500 الائتمانية الشيكات.To build a traditional ABC model for this department, you would survey employees to estimate the percentage of time they spend (or expect to spend) on the three activities and then assign the department’s resource expenses according to the average percentages you get from the survey. Let’s say employees report that they spend (or expect to spend) about 70% of their time on customer orders, 10% on inquiries or complaints, and 20% on credit checks. This implies, under ABC, that each order consumes $8 of resource expense, each inquiry $40, and each credit check $44.80, as shown in the exhibit “Doing ABC the Traditional Way.” Armed with these figures, known as the cost-driver rates, managers can assign the costs of the department’s resources to the customers and products that use its services.Doing ABC the Traditional WayThis approach works well in the limited setting in which it was initially applied, typically a single department, plant, or location. Difficulties arise, however, when you try to roll this approach out on a large scale for use on an ongoing basis. In one large bank’s brokerage operation, the ABC data-gathering process required 70,000 employees at more than 100 facilities to submit monthly reports of their time allocation. The company employed 14 people full-time just to manage the data collection, processing, and reporting.متطلبات الوقت والتكلفة لخلق والحفاظ على نموذج ABC بهذا الحجم يشكل عائقا كبيرا لاعتمادها على نطاق واسع في معظم الشركات. النموذج تقديرات تكاليف العملية والمنتج والعميل حيث يتم تحديث النظم التي وضعت في المكان النادر (بسبب التكاليف التي رينتيرفيوينج وريسورفيينج)، سرعان ما تصبح غير دقيقة. ما هو أكثر من ذلك، الناس يضيعون وقتهم يتجادلون حول دقة معدلات التكلفة-سائق مستمدة من معتقدات الأفراد الذاتية بدلاً من معالجة أوجه القصور التي يكشف النموذج: عدم كفاءة العمليات والمنتجات غير المربحة والعملاء والقدرة الزائدة.أيضا في كثير من الأحيان تفشل ABC النماذج التقليدية لالتقاط الطابع المعقد للعمليات الفعلية. النظر في نشاط "سفينة النظام للعملاء." بدلاً من افتراض ثابت التكلفة لكل أمر يتم شحنها، قد ترغب شركة تعترف الفروق في التكلفة عندما يتم شحن طلبية في شاحنة كاملة، في أقل من حمولة شحنة (ليتا)، استخدام إكسبريس بين عشية وضحاها، أو عن طريق شركة تجارية. وبالإضافة إلى ذلك، قد دخل بالترتيب في النظام أما يدوياً أو إلكترونيا، وقد يكون معياراً أو حركة معجلة. للسماح بتفاوت كبير في الموارد المطلوبة بترتيبات النقل البحري المختلفة، يجب إضافة أنشطة جديدة إلى النموذج، مما يوسع من تعقيده.As the activity dictionary expands—either to reflect more detail about activities or to expand the scope of the model to the entire enterprise—the demands on the computer programs used to store and process the data escalate. Suppose a company has 150 activities in its enterprise ABC model, applies the costs in these activities to some 600,000 cost objects (products and customers), and runs the model monthly for two years. That would require data estimates, calculations, and storage for more than 2 billion items.Such expansion has caused ABC systems to exceed the capacity of generic spreadsheet tools, such as Microsoft Excel, and even many ABC software packages. The systems could take days to process one month’s worth of data. For example, the automated ABC model for Hendee Enterprises, a $12 million fabricator of awnings, took three days to calculate costs for its 40 departments, 150 activities, 10,000 orders, and 45,000 line items.وأصبحت هذه المشاكل الواضحة لمعظم ABC المستفيدون. ولكن ظهرت مشكلة خفية وأكثر جدية من عملية دراسة الحالة والمقابلة نفسها. عند الناس تقدير مقدار الوقت الذي يقضونه على قائمة بالأنشطة التي سلمت لهم، أنهم دائماً تقرير النسب المئوية التي إضافة تصل إلى 100. عدد قليل من الأفراد التقرير أن نسبة مئوية كبيرة من وقتهم الخمول أو غير مستخدمة. ولذلك، تحسب معدلات التكلفة--السائق على افتراض أن الموارد تعمل بكامل طاقتها. ولكن كما نعلم جميعا، عمليات تشغيل غالباً ما يقل كثيرا عن قدرتها. وهذا يعني أن معدلات تكلفة التشغيل المقدرة عادة مرتفعة جداً. (من الناحية الفنية، أنهم سوف يكون مبالغا فيها بالمعاملة بالمثل النسبة المئوية لاستخدام قدرة: في استخدامها 80%، وهي المعدلات 25% مرتفعة للغاية؛ وفي استخدامها 67%، والمعدلات 50 ٪ مرتفعة للغاية.)أي بي سي الجديدحل المشاكل مع أية بي سي عدم التخلي عن المفهوم. أي بي سي بعد كل ساعد العديد من الشركات تحديد فرص تحسين التكلفة والربح هامة من خلال التسعير علاقات العملاء غير مربحة، عملية إدخال تحسينات على الورشة وتصميمات المنتج أقل تكلفة، وتنوع المنتجات الترشيد. إمكاناتها على نطاق واسع يمثل فرصة كبيرة للشركات. لحسن الحظ، التبسيط الممكن الآن من خلال اتباع نهج ندعو يحركها وقت ABC، الذي ساعدنا بنجاح أكثر من 100 شركة العميل تنفيذ، بما في ذلك تلك الموضحة في هذه المقالة. في النهج المنقح، مديري مباشرة تقدير متطلبات الموارد تفرضها كل معاملة أو المنتج أو العميل بدلاً من تعيين تكاليف الموارد أولاً للأنشطة، ومن ثم إلى المنتجات أو العملاء. لكل مجموعة من الموارد، أن تقديرات معلمتين فقط المطلوبة: التكلفة لكل وحدة زمنية لتوفير قدرات الموارد والأوقات وحدة استهلاك قدرة المورد من المنتجات والخدمات والزبائن. في الوقت نفسه، يوفر النهج الجديد أكثر دقة معدلات التكلفة-سائق بالسماح مرة وحدة تقدير حتى بالنسبة للمعاملات المعقدة المتخصصة.في النهج المنقح، تقدير مديري مباشرة في الطلب على الموارد تفرضها كل المعاملات، والمنتج، أو العملاء.تقدير التكلفة لكل وحدة زمنية من القدرات.Instead of surveying employees on how they spend their time, managers first directly estimate the practical capacity of the resources supplied as a percentage of the theoretical capacity. There are various ways to do this. As a rule of thumb, you could simply assume that practical full capacity is 80% to 85% of theoretical full capacity. So if an employee or machine is available to work 40 hours per week, its practical full capacity is 32 to 35 hours per week. Typically, managers would allot a lower rate—say 80%—to people, allowing 20% of their time for breaks, arrival and departure, communication, and training. For machines, managers might allot a 15% differential between theoretical and practical capacity to allow for downtime due to maintenance, repair, and scheduling fluctuations. A more systematic approach, perhaps, is to review past activity levels and identify the month with the largest number of orders handled without excessive delays, poor quality, overtime, or stressed employees. Whichever approach you prefer, it’s important not to be overly sensitive to small errors. The objective is to be approximately right, say within 5% to 10% of the actual number, rather than precise. If the estimate of practical capacity is grossly in error, the process of running the time-driven ABC system will reveal the error over time.Returning to our example, let’s assume that the customer service department employs 28 reps to do the frontline work and that each puts in eight hours per day. In theory, therefore, each worker supplies about 10,560 minutes per month or 31,680 minutes per quarter. The practical capacity at about 80% of theoretical is therefore about 25,000 minutes per quarter per employee, or 700,000 minutes in total. Since we already know the cost of supplying capacity—the $560,000 in overhead costs—we can now calculate the cost per minute of supplying capacity ($0.80).The capacity of most resources is measured in terms of time availability, but the new ABC approach can also recognize resources whose capacity is measured in other units. For example, the capacity of a warehouse or vehicle would be measured by space provided, while memory storage would be measured by megabytes supplied. In these situations, the manager would calculate the resource cost per unit based on the appropriate capacity measure, such as cost per cubic meter or cost per megabyte.Estimating the unit times of activities.Having calculated the cost per time unit of supplying resources to the business’s activities, managers next determine the time it take
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