Working Capital and Cash: The Cash Conversion Cycle

Working capital — the cash tied up in receivables and inventory, less payables — is one of the biggest drivers of a company's cash, and managing it can free or trap large amounts. Every pound sitting in an unpaid customer invoice or a warehouse of inventory is cash the business has locked up; every pound of supplier credit is cash it's holding onto. Treasury cares because working capital swings directly drive the cash position and forecast — and because freeing working capital is a source of internal funding that costs no interest. A company can generate serious cash just by managing working capital better, before it borrows a penny.

What it is, in cash terms

Forget the balance-sheet definition for a moment and think in cash: working capital is the cash stuck in the machinery of running the business. Money customers owe you (not yet cash), money invested in inventory (not yet sold), minus money you owe suppliers (cash you're still holding). When that stuck amount grows, it absorbs cash; when it shrinks, it releases cash.

The cash conversion cycle

The standard measure is the cash conversion cycle (CCC) — how long cash is tied up before it comes back:

CCC = DSO + DIO − DPO (Days Sales Outstanding + Days Inventory Outstanding − Days Payables Outstanding)

• DSO — how long customers take to pay you.
• DIO — how long inventory sits before it's sold.
• DPO — how long you take to pay suppliers.

A shorter cycle ties cash up for less time — so less cash is locked in working capital. Shorten it and you release cash; let it drift longer and you absorb it.

The three levers

Each component is a lever on cash:

Note the last column: the levers mostly sit outside treasury. Which is exactly why treasury has to engage on working capital rather than just observe it.

Why treasury cares

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Working capital is the cheapest funding a company has — cash it already owns, locked in its own operations. Freeing it costs no interest and needs no bank. Ignoring it means borrowing money you were sitting on all along.

Two reasons treasury can't ignore working capital. First, it's a huge, interest-free source of funding: the cash released by cutting the conversion cycle is cash you don't have to raise. Second, working capital movements drive the cash position and forecast — a big receivables build or an inventory season swings cash hard, and treasury has to anticipate those swings to manage liquidity.

The tension in DPO

One honest caution: stretching payables (DPO) frees your cash, but it does so by holding onto suppliers' cash — pay too slowly and you damage supplier relationships and their liquidity, sometimes at real cost to your own supply chain. Working-capital optimization has an ethical and commercial limit; the goal is efficient working capital, not squeezing suppliers to paper over your own cash management. (This tension is part of why supply chain finance exists — arrangements that let suppliers get paid early while the buyer keeps longer terms, easing both sides.)

What usually goes wrong

• Ignoring working capital as a cash source. Borrowing externally while large cash sits locked in receivables and inventory.
• Gaming DPO at suppliers' expense. Freeing cash by paying suppliers punishingly late, damaging the supply chain.
• Not forecasting working-capital swings. Missing the big seasonal or growth-driven cash movements working capital causes, so liquidity is managed blind.
• Treasury staying passive. Treating working capital as "someone else's function" when its cash impact is treasury's problem.

Understand the cash conversion cycle, engage on the three levers even though they sit in other functions, respect the supplier tension in DPO, and forecast the swings — and working capital becomes what it should be: the first, cheapest source of cash a company reaches for. It's the liquidity hiding inside the business's own operations.

Part of the Cash & Liquidity Management guide. See also corporate funding and credit facilities and liquidity risk management. The newsletter sends one finance-systems pattern every two weeks.