What lean accounting is
Lean accounting reports results by value stream instead of by product or department, using actual costs for the period rather than allocated standard costs. It exists because traditional costing rewards overproduction and hides the gain from cutting inventory and lead time.
Instead of asking "what does each part cost?", the question becomes "how much did the value stream bill and spend this week?". The statement fits on one page and the shop floor can read it.
Lean accounting visual map
The map shows the contrast with standard costing, the value stream statement and the box score.
Why standard costing works against lean
Under absorption costing, fixed cost is divided by units produced. The more you build, the lower the unit cost and the higher the book profit, even when part of the output goes to stock. Here is a fictional example: price $80, variable cost $30 per unit, fixed cost for the period $20,000, and 800 units sold.
| Measure | A: builds 1,000 | B: builds 800 |
|---|---|---|
| Fixed cost per unit | $20.00 | $25.00 |
| Absorbed unit cost | $50.00 | $55.00 |
| Book profit (absorption) | $24,000 | $20,000 |
| Profit using actual period costs | $14,000 | $20,000 |
| Ending inventory | 200 units | 0 |
Scenario A looks better on the income statement ($24,000 versus $20,000), but it spent $6,000 more on material and labor that now sits in 200 units. Comparing cash on actual costs shows the opposite: $14,000 versus $20,000. That is the wrong incentive for anyone pursuing just-in-time and continuous flow.
Value stream costing
A value stream includes everything needed to deliver a product family to the customer, as defined in value stream mapping (VSM). In lean accounting, costs go straight to the stream, with no machine-hour allocation:
- Materials purchased for the stream in the period.
- Labor of the people dedicated to the stream, treated as a fixed team cost.
- Equipment and maintenance used by the stream.
- Facilities, based on the floor area the stream occupies.
- Dedicated support, such as the stream's quality and logistics staff.
Corporate costs that belong to no stream stay out, or sit at a separate level, with no arbitrary allocation.
Example: weekly value stream statement
Fictional example: the "Valves" stream sells 2,000 units per week at $60.
| Line | Calculation | Weekly amount ($) |
|---|---|---|
| Revenue | 2,000 × 60 | 120,000 |
| Materials | purchases for the week | 48,000 |
| Labor | 15 people × 1,400 | 21,000 |
| Equipment and maintenance | stream costs | 6,000 |
| Facilities | floor area occupied | 3,000 |
| Dedicated support | quality and logistics | 4,000 |
| Total stream cost | 48,000 + 21,000 + 6,000 + 3,000 + 4,000 | 82,000 |
| Stream profit | 120,000 − 82,000 | 38,000 |
Stream margin = profit ÷ revenue = 38,000 ÷ 120,000 ≈ 31.7%
Cost per unit sold is 82,000 ÷ 2,000 = $41.00, and unit margin is $19.00. Nobody needs an allocation table to get these numbers.
The box score
The box score puts operational, capacity and financial measures on the same page. In the example, the stream cut inventory from $328,000 to $213,200 after improvements.
| Measure | Before | After | How to calculate |
|---|---|---|---|
| Inventory turns | 13 | 20 | (82,000 × 52) ÷ inventory = 4,264,000 ÷ 328,000 and ÷ 213,200 |
| Days of inventory | 20 | 13 | inventory ÷ daily cost (82,000 ÷ 5 = 16,400) |
| Sales per person per week | $8,000 | — | 120,000 ÷ 15 |
| Available capacity | 60 h | — | 600 h − 390 h productive − 150 h non-productive |
Of the stream's 600 weekly hours (15 people × 40 h), 390 are productive (65%), 150 are losses such as waiting, rework and setup (25%), and 60 are free (10%). At $35 per hour (21,000 ÷ 600), the free capacity is worth $2,100 per week, and it only becomes money if used for more sales or redeployed, never by reflex layoffs. See also inventory turnover.
How to implement in 5 steps
- Define the value streams by product family, using VSM.
- Assign people, machines and floor area to each stream.
- Build the weekly statement with actual costs, in the format of the example.
- Create the box score and review it in daily lean management.
- Keep standard costing only for what law and auditors require, in parallel, until the transition is done.
Common mistakes
- Still measuring efficiency per machine hour, which reopens the incentive to overproduce.
- Allocating corporate costs to the streams "to make the numbers add up".
- Laying off the freed capacity, which destroys trust in improvement work.
- Confusing the management report with official accounting: statutory reporting and audits still require the applicable rules.
- Updating the statement only at month end, losing the effect of fast action.
Frequently asked questions
What is lean accounting?
A management model that tracks costs and results by value stream, using actual period data and no allocation of indirect costs.
How is it different from standard costing?
Standard costing divides fixed costs by units produced and rewards overproduction. Lean accounting shows the stream's real spend for the period.
What is a box score?
A table of operational, capacity and financial measures for the stream, such as inventory turns, sales per person and free capacity.
How are inventory turns calculated in the example?
Annual cost of 82,000 × 52 = 4,264,000, divided by 328,000 gives 13 turns. With inventory at 213,200, it is 20 turns.
Does it replace statutory accounting?
No. It complements standard costing with decision information, while statutory accounting follows the applicable standards.
Sources
- MASKELL, B. H.; BAGGALEY, B. Practical Lean Accounting. New York: Productivity Press, 2004.
- MASKELL, B. H.; BAGGALEY, B.; GRASSO, L. Practical Lean Accounting. 2nd ed. Boca Raton: CRC Press, 2011.
- WOMACK, J. P.; JONES, D. T. Lean Thinking. New York: Simon & Schuster, 1996.
- JOHNSON, H. T.; KAPLAN, R. S. Relevance Lost. Boston: Harvard Business School Press, 1987.
Keep studying: trusted sources and links
- Lean Enterprise Institute: What is Lean?
- Lean Enterprise Institute: Lean Lexicon, Value Stream Mapping
- Wikipedia: Lean manufacturing
- Wikipedia: Value-stream mapping
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About the author
Lean Manufacturing & Behavioral Management Specialist
Over 20 years in the automotive and metalworking industries (GM and Dana), Lean Manufacturing practitioner since 2006. SENAI instructor and mentor in Brazil’s Brasil Mais Produtivo program, delivering consulting, training and audits for 50+ companies, combining quality, productivity and people development.
