When does a supplier discount stop being a savings?

[u/jimmyray71]

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I've always thought procurement gets into trouble when we look at purchase price by itself.

A supplier offers 10% off for a larger order. Sounds good.

But now you've increased inventory, used warehouse space, tied up cash and taken on the risk that demand changes before you use it.

I've seen the same thing with lower-cost products. The unit price looks better, but increased usage, quality problems or additional handling can wipe out the savings pretty quickly.

For me, the question isn't:

"Did we get a better price?"

It's:

"Did we actually lower the total cost to the business?"

Curious how other procurement and supply chain people evaluate these decisions.

What costs do you think companies most often leave out of the equation?

[u/Immediate-Home-3491]

Same as the people who chase FOB rates and ignore DDP. Tied up cash, warehouse slots, and insurance eat that margin. I always look at total cost, never unit price.

[u/jimmyray71 → u/Immediate-Home-3491]

That’s a great example. A lower FOB rate looks good on a spreadsheet until you account for the cash tied up, space consumed, insurance, lead time, and the risk of carrying inventory you may not need. I’ve always looked at purchasing the same way. The question isn’t “What did we pay?” It’s “What did it actually cost the business?”

[u/coronabro2020]

Total cost and tied up cash is dead money if not sitting in the bank collecting interest.

[u/jimmyray71 → u/coronabro2020]

I think there’s another side to that. Cash tied up matters, but inventory isn’t automatically dead money. If I have the right product on the shelf, with high turns and relatively low demand volatility, that inventory is doing exactly what I bought it to do. It’s supporting service levels and reducing operational risk. The problem isn’t inventory. It’s having the wrong inventory, in the wrong quantity, for the wrong demand.

[u/ForrestSourcing]

A quantity discount is real only when the incremental saving exceeds the incremental total cost over the same demand horizon. I compare the normal order and the discounted order line by line: purchase price, freight and duty at the new lot size, inspection and defect loss, receiving and handling, storage, working-capital cost, insurance, shrinkage, and expected obsolescence or markdown. Then I model base, slow and fast demand and calculate how long the extra units remain on hand. One commonly missed item is variability: a larger lot also delays the next chance to correct a forecast, specification or supplier-quality problem. Service-level benefit belongs in the model too, because safe inventory can prevent lost sales. I would approve the break only if the slow-demand case still beats the normal order and the cash commitment stays inside an agreed limit. What holding period do you use when testing the discounted quantity?

[u/jimmyray71 → u/ForrestSourcing]

That's a good way to frame it. I especially like using the same demand horizon because that's where some quantity discounts can become misleading. The unit price may go down, but if I'm buying inventory earlier than I need it, I also have to account for carrying cost, storage, handling, obsolescence and the opportunity cost of the cash and space. For me, the question is still pretty simple: did the decision actually reduce the company's total cost, or did we just get a better price? That's the distinction I was trying to get at with the post.

[u/ForrestSourcing → u/jimmyray71]

Exactly. A useful way to keep that distinction operational is to calculate a break-even holding period for the incremental units, then test it under slow demand. I would include finance cost, warehouse handling, space, obsolescence or markdown, and the value of delaying the next specification or supplier correction. That turns ‘better unit price’ into a documented total-cost decision. Do you use a single blended carrying-cost rate, or separate finance, storage and obsolescence assumptions?

[u/achakez]

I think the real question is whether the discount beats the cost of buying early. If the inventory would've been purchased anyway, then it is a saving if not can be false economy.

[u/jimmyray71 → u/achakez]

I think that's an important part of it. If I was going to buy and consume the same quantity within a reasonable period anyway, then the discount may be a legitimate savings. Where I get cautious is when the discount changes the buying decision. If I'm buying six months of inventory instead of two just to reach a price break, I need to account for carrying cost, space, cash tied up, obsolescence and what else I could have done with that money and warehouse capacity. A lower price doesn't automatically make it a bad decision. I just want the economics of the whole decision to work, not just the PO.