Why Is an Increase in Working Capital a Cash Outflow?

Working capital is cash tied up in running a business. When it goes up, you've either paid for something the income statement hasn't expensed yet, or booked revenue you haven't collected. Either way the cash left, or never arrived, and net income doesn't show it. The cash flow statement subtracts the difference to get you back to reality.

Where the confusion comes from

Working capital is current assets minus current liabilities. Two different things can make that number go up, and they feel like opposites:

• Current assets go up. More receivables, more inventory. Cash went out or never came in.
• Current liabilities go down. You paid down payables. Cash went out.

Both increase working capital, and both consume cash. The trap is the mirror image: when accounts payable goes up, that's a cash inflow, and it decreases working capital. People who memorize “an increase in working capital is a cash outflow” without the asset and liability split get stuck when an interviewer asks about payables.

A good way to think about it is that the cash flow statement is a reconciliation. It starts with net income and “corrects” for every place the income statement and the bank account disagreed about timing.

Line by line

Every line is the same question: did the income statement and the cash move at the same time, and if not, which way is the gap?

Why a profitable company can run out of cash

This is what the question is really getting at.

Take a business earning a 10% net margin. In one year it grows revenue from $100m to $150m. Growth means carrying more receivables and more inventory: say receivables rise $20m, inventory rises $15m, and payables rise $8m. Compare that to the same business standing still.

Same business, same margin. Growing, it earns $15m and burns $7m of cash. Standing still, it earns $10m and generates $15m.

Read that again: the growing company earned 50% more profit and still ran out of money. Nothing went wrong. The company sold more, and selling more meant buying inventory and extending credit before customers paid. Growth consumed $27m of cash, which the income statement never showed. This is how profitable companies go under.

Negative working capital runs the other way

Some businesses collect before they deliver. A software company billing annually in advance, a gym selling memberships, a restaurant taking cash at the till while paying suppliers on 30-day terms.

For those, growth generates cash. In the first two cases deferred revenue rises with every new customer; in the restaurant's case it's payables. Both are current liabilities, so working capital falls and the cash flow statement adds the change back. The business is funded by its own customers and suppliers.

That's worth knowing as a business model point, not just an accounting one. It's a large part of why subscription businesses can grow faster than their profits should allow, and why a retailer with negative working capital can expand without raising money.

One definitional thing that confuses people in a model

“Working capital” in accounting includes cash and short-term debt. That's not useful for modeling.

What you actually forecast is operating working capital, which excludes cash and any debt maturing within a year. Both exclusions exist for the same reason: cash is what you're trying to solve for, so leaving it in the calculation is circular, and short-term debt is a financing item, not an operating one.

If someone asks you to project working capital, they mean the operating version, usually driven as a percentage of revenue or COGS, or off days (receivable days, inventory days, payable days).

Why the number won't tie to the balance sheet

Take the change in each balance sheet line between two years and it often won't match the working capital figure on the cash flow statement. That's not uncommon¹. The usual causes:

• An acquisition brought in receivables and inventory that were bought, not earned
• Foreign exchange moved a balance without any cash changing hands
• A line was reclassified between periods

The cash flow statement only wants the piece that represents actual operating cash movement. The balance sheet delta includes everything.

Answering it in an interview

The fast version: working capital is cash tied up in operations, so when it rises you've either paid for something you haven't expensed or booked revenue you haven't collected. Net income missed both, so the cash flow statement subtracts the difference.

If they push, get specific. Receivables are the easiest example: you recorded the sale, so net income went up, but no money arrived, so you subtract it.

If they ask about payables: payables going up is a source of cash, because you took the expense without paying for it yet.

Three answers to avoid:

• “Because working capital is an asset.” It's an asset minus a liability.
• Reciting the sign convention without the timing reason.
• Confusing working capital definitions. In banking we pretty much always mean operating working capital, which excludes cash and debt.

Takeaways

An increase in working capital is a cash outflow because it means cash left the business before the income statement recorded it, or revenue was recorded before the cash arrived. Current assets up means cash out. Current liabilities up means cash in. Growth consumes working capital, which is how a profitable company runs out of money, and businesses that collect in advance get the opposite effect. What you model is operating working capital, excluding cash and short-term debt.