Why a Shopify discount disappears at checkout, and how to fix it

You set up a discount, test it, and it works. Then a sale goes live and the same discount stops showing at checkout. Nothing is broken and no error appears. Most of the time, Shopify has compared two discounts that can't run together and kept one.

It tends to surface in the run-up to Black Friday, when a store adds a sitewide offer on top of gifts, upsells and bundles that have been running all year.

How Shopify decides

Shopify discounts come in three classes: product, order and shipping. Each discount has settings for which of those classes it can combine with.

When two discounts apply to the same cart and aren't allowed to combine, Shopify doesn't warn anyone. It keeps the deal that is better for the buyer and drops the other. The buyer never sees that a choice was made, and neither do you.

What it looks like

Here's a case from our own testing. A store had a product discount worth €4 on an upsell, and an order discount of 20% over €200 that did not combine with product discounts. Under €200 the upsell discount worked. Over €200 Shopify kept the 20%, and the upsell showed its full price at checkout, even though the discount function had returned the €4 as expected.

That last part is what makes this slow to debug. The app's logs say the discount was sent, because it was. Shopify removed it afterwards.

How to check your store

1. Open Discounts in Shopify admin and list everything active or scheduled for your sale.
2. For each one, read its Combinations setting.
3. For any two that could hit the same cart, ask whether they are allowed to combine. Both sides have to allow it.
4. Build a cart that qualifies for both and look at the checkout total.

App discounts count too. Free gift discounts, upsell offers and bundle discounts all follow the same combination settings.

Which setting to choose

Letting everything combine isn't the safe answer, because stacked discounts eat margin. Work out which combinations you are happy to pay for:

• Free gift with a sitewide percent off. Often fine if the gift is cheap, but run the numbers at your lowest qualifying cart. This margin guide has worked examples.
• Upsell discount with an order discount. Allow it if the upsell is a real add-on. Without it, your best spenders lose the offer.
• Two percent-off offers. Rarely worth allowing.

Other reasons a discount goes missing

• It expired. Check the end date and time zone.
• The cart changed. A buyer removed the product that earned it.
• The buyer isn't eligible. Customer segments and usage limits apply.
• The cart is very large. Shopify Functions run under an instruction limit, so a function may skip a cart with an unusually high number of lines.

Before a sale, add this test to your Black Friday checkout checklist: build one cart that qualifies for everything at once and read the total line by line.