Inventory Purchases: Cash Timing vs Goods Sold

Inventory affects profit when its cost is recognized for goods sold, while cash changes when the supplier is paid. Those dates often differ. A business can buy stock for future sales, sell stock purchased earlier, or receive stock before the invoice is due. A useful forecast needs both the inventory rollforward and the payment schedule.

Follow units and dollars together

Suppose a business begins a month with 100 units costing $20 each. It purchases another 300 identical units at $20, then sells 250 units. Ignoring losses and other inventory costs, ending inventory is 100 + 300 − 250 = 150 units, valued at $3,000. Cost of goods sold is 250 × $20 = $5,000. Purchases total $6,000.

If the $6,000 purchase is paid in full this month, cash payments exceed goods-sold expense by $1,000. That amount corresponds to the increase in inventory value from $2,000 to $3,000. It is not an extra $1,000 loss. It is cash committed to stock that remains on hand under the example assumptions.

Layer in supplier terms

Now assume the same purchase requires 50% payment when ordered and 50% next month. This month's purchase payment is $3,000 and the remaining $3,000 is scheduled later. The inventory receipt and goods-sold calculation do not change solely because the payment terms changed. If an old $2,000 supplier invoice is also due this month, total inventory-related payments become $5,000.

Track purchase orders, goods receipts, invoices, and payments as linked events. An order placed near month end may require a deposit now but arrive next month. Putting it entirely in the arrival month understates the current cash requirement. Conversely, paying an old invoice is not a new inventory purchase for the current month's units schedule.

Test the slow-sales case

If only 150 units sell, ending stock rises to 250 units and cost of goods sold falls to $3,000. A supplier payment already committed does not automatically fall with sales. The slower-sales case can therefore consume more cash relative to revenue while leaving more inventory on the balance sheet.

Check physical counts, returns, spoilage, and landed costs using the business's actual inventory policy. This example assumes identical unit costs and does not choose a valuation method. Avoid treating all stock as immediately convertible to cash at its book value. The cash plan needs a realistic sales and collection schedule, while the inventory plan needs feasible quantities and delivery dates.

Method references: OpenStax: Prepare Financial Budgets. Accessed October 22, 2026. All dollar figures are hypothetical worked examples.