Working-capital adjustments in CFO cause more sign errors than everything else combined, because people memorize rules they don't believe. Derive it once, from first principles, and you'll never flip a sign again.
How do two questions give the right sign?
Net income counts revenue you may not have collected and expenses you may not have paid. The CFS must undo both. Ask two questions of any operating balance-sheet line:
Q1: is it an operating asset or an operating liability? Q2: did it go up or down?
- An operating asset going up absorbs cash. If receivables are up ₹10, then ₹10 of the revenue in net income was never collected. Profit overstates cash, so subtract. If inventory is up, you paid (or owe) for goods that haven't sold. That cash is sitting on a shelf, so subtract. Assets absorb.
- An operating asset going down releases cash. Old receivables get collected and old inventory gets sold, so add.
- An operating liability going up lends you cash. If payables are up ₹10, suppliers financed ₹10 of your costs. Your expense hit net income but not your bank account, so add. If deferred revenue is up, customers paid you before you earned it, so add. Liabilities lend.
- An operating liability going down repays that lending, so subtract.
Put shortly, an asset going up means cash down and a liability going up means cash up, and the reverses hold too. On the CFS this appears as − Δ operating assets + Δ operating liabilities, where Δ means closing minus opening.
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What should you watch for when applying the sign rule?
Two boundary rules keep you out of trouble. First, "operating" excludes cash itself and excludes financing items. Debt and dividends belong to CFF, and the cash line is the answer you're solving for. Second, take deltas from the balance sheet you're actually linking. In real filings the CFS working-capital lines rarely equal raw BS deltas, because acquisitions, FX and reclassifications get in the way. Later in the program, the filing capstone and the full spreadsheet model handle that. In this clean textbook world they tie exactly, and you should make them tie.
Here's a preview of the interpretation, from the liquidity-and-leverage ratio module ahead. A growing company normally consumes working capital. Its AR and inventory scale with revenue. When CFO runs persistently far below net income because working capital balloons faster than sales, that's a first-class red flag, and the earnings-games module ahead teaches it in full. The linkage is what lets you see it.