Purchase Order Management: How to Run a Buying Operation That Does Not Create Cash Flow Problems

Why PO management is a financial discipline, not just an operations function#

Every purchase order is a cash commitment — either an immediate payment or a future obligation. A PO for £50,000 of inventory placed today will result in either immediate payment (if you pay upfront, common with new suppliers) or an invoice due in 30-60 days. If that inventory does not sell as planned, you have committed cash to stock that is not generating returns. Viewing purchase orders as financial decisions — not just operational transactions — changes how they are evaluated and approved.

The open-to-buy framework for buying discipline#

Open-to-buy (OTB) is the inventory purchasing budget for a defined period. OTB = Planned Sales + Planned End-of-Period Stock − Opening Stock − Stock on Order. If planned monthly sales are £80,000 at cost, desired closing stock is £120,000 at cost, opening stock is £110,000, and stock on order is £30,000: OTB = £80,000 + £120,000 − £110,000 − £30,000 = £60,000. You can commit to up to £60,000 of new purchase orders this month without exceeding your inventory plan. OTB discipline prevents overbying — the root cause of most dead stock and overstock positions.

Payment terms and their cash flow impact#

Supplier payment terms are one of the most powerful cash flow levers in a buying operation. The difference between 30-day payment terms and 60-day payment terms on a £500,000 annual purchasing budget is approximately £41,000 in average additional cash available throughout the year. Negotiating extended payment terms should be a priority in every supplier relationship once you have established a track record. Payment on delivery (POD) is the most cash-flow-friendly for the buyer, as the inventory is already in transit when payment is due. Letters of credit extend the cash timing even further but add banking cost.

Managing supplier minimums and their impact on OTB#

Minimum order quantities (MOQs) imposed by suppliers force buyers to commit to larger quantities than demand alone would justify — creating overstock risk for lower-velocity SKUs. The negotiation objective is to reduce MOQs over time as the supplier relationship matures and your track record as a reliable customer is established. In the interim, manage MOQ overstock risk by using new product launches (where you must meet MOQ to access the product at all) as an opportunity to negotiate the lowest possible MOQ, and by qualifying multiple products from the same supplier so that the MOQ requirement can be met across a range of products rather than one.

Using AskBiz to manage purchase orders and OTB#

AskBiz tracks your open purchase orders against your planned inventory position and OTB budget — showing you how much budget you have committed and how much remains available. It flags situations where planned purchase orders would create overstocked positions given current sales velocity, and identifies products where the reorder point has been triggered but no purchase order is yet in place. Ask it: what is my current OTB position for this month, which open purchase orders are creating projected overstock positions given current velocity, which products need a purchase order placed immediately based on current stock and reorder point.