“I put in SUMMER20 and nothing came off.”

Every discount in Shopify has three combination settings: whether it combines with product discounts, with order discounts, and with shipping discounts. Two discounts are used together only when each one allows the other’s kind. One side allowing it isn’t enough.

In this cart, Buy three, get 30 percent off is an automatic product discount, and SUMMER20 an order discount. SUMMER20 allows combining with product discounts; Buy three doesn’t allow order discounts. So Shopify used one of them, the bigger saving: with SUMMER20 alone the cart would cost $1,679.88, with Buy three alone $1,469.91. The customer pays $1,469.91 and sees the code do nothing.

When both discounts are set not to combine, the sentence names both settings. When one allows it and the other doesn’t, as here, it adds which one does and which one blocks.

• Each discount’s kind (product, order or shipping) and its three combination settings.
• The cart, priced by Shopify, and the discounts it applied.
• The same cart priced again with each discount alone, for the two totals above. They show what the customer would have paid either way.

• If they should stack: open the discount that blocks (here Buy three, get 30 percent off) and turn on combining with the other’s kind (order discounts). Both must allow it.
• If they shouldn’t: turn off combining in the other one too (here SUMMER20 with product discounts), so its settings say what happens.

Combinations lists every pair like this in your store, the discounts that block the most first, before a customer runs into one.