Throughput Accounting 2 · Lesson 2 of 6
Throughput, investment and operating expense
Welcome to simple, common-sense accounting. Money flows in through sales, out through truly variable cost and operating expense, and sticks inside as investment. Learn the definitions precisely, and why products don’t make profit, the company does.
What is the goal?
Before choosing measures, agree on the goal. For a company run for profit, the goal is to make more money, now and in the future. Every measure should tell us whether a decision moves us towards it. Throughput accounting does this with three measures and a picture of how money moves through the business.
How money moves
- Sales (S) bring money in.
- Truly variable cost (TVC) flows out with each unit sold: what you buy specifically for the things you sell.
- Investment (I) is money that sticks inside the system: stock, machines, buildings, money that can be turned into more sales later.
- Operating expense (OE) is the money the system spends to turn investment into throughput. It is a cost of the period, not of a product.
The definitions, precisely
Throughput (T) is the rate at which the system generates money through sales: T = sales − truly variable cost. A cost is truly variable only if it changes with every single unit sold: raw material, bought-in parts, piece-rate subcontracting, sales commission per unit, freight per unit. Throughput counts when the sale happens, not when the product is made.
Investment (I) is all the money tied up in the system: raw material, work in progress and finished goods, valued at truly variable cost only, plus machines, buildings and other assets.
Operating expense (OE) is all the money the system spends to turn I into T: wages and salaries, including direct labour, rent, power, maintenance, depreciation, interest.
Exercise: where does each one belong?
- Steel bought for each product
- Monthly wages of machine operators
- Finished goods waiting in the warehouse
- Courier charge per parcel delivered to a customer
- Electricity for the plant
- A new machine
- A sales agent’s commission of 3% per order
- The quality manager’s salary
Products don’t make profit, the company does
In throughput accounting, profit is made when the company’s total throughput exceeds its operating expense. No single product makes a profit; each contributes throughput to cover one shared operating expense.
Every month, throughput accumulates. Once it crosses the year’s operating expense, every further rupee of throughput is profit. This gives two clear accountabilities:
- Sales is accountable for staying on the budgeted throughput curve.
- Each head of operating expense is accountable for cost control: spending in line with plan, not cutting for its own sake.
If throughput grows faster than operating expense, profit grows.
The two key measures
In a company run for profit, the goal is measured in money, the same units as operating expense. Two measures follow:
- Net profit = T − OE, the absolute measure.
- Return on investment = (T − OE) ÷ I, the relative measure.
And one more you can derive: cash flow = net profit plus or minus the change in investment. Building stock reduces cash; selling it down releases cash.
For the P&Q plant on its best week: T = ₹6,300, OE = ₹6,000, so net profit is ₹300. No allocation anywhere.
Pause and think: why does throughput count only when a unit is sold, not when it is made?
- Because accountants prefer it
- Because making is easier to measure
- Because money comes into the system only through sales; a unit in the warehouse is still investment
- Because production is the constraint
That one choice removes the artificial inventory profits of Part 1.
Check your understanding
Answer all five. Get four right to complete the lesson.
1. Throughput is…
- Units produced per day
- Sales minus truly variable cost
- Sales minus all costs
- Revenue per employee
The rate at which the system generates money through sales.
2. Operators’ monthly wages are…
- Truly variable cost
- Investment
- Part of product cost only
- Operating expense
They don’t change with each unit made.
3. Inventory is valued at…
- Truly variable cost
- Full product cost
- Selling price
- Zero
So making for stock never creates profit on paper.
4. Return on investment in throughput terms is…
- T ÷ OE
- (T + OE) ÷ I
- (T − OE) ÷ I
- I ÷ T
Net profit divided by investment.
5. In throughput accounting, profit is made when…
- Each product’s price exceeds its cost
- Total throughput exceeds total operating expense
- Machines are fully used
- Inventory rises
Products don’t make profit; the company does.