Help with paid product options on Shopify

How-to articles for stores that sell paid options such as engraving, gift wrap or personalization. Each one starts with checks you can do yourself in Shopify admin.

• Paid product option not charged on a Shopify order: how to checkA customer picked a paid option like engraving or gift wrap, but the order doesn't include the fee. How to confirm it on one order and find others.
• A discount code made the add-on free: how to fix itWhy a Shopify discount code can bring a gift wrap or engraving add-on to $0, and how to limit the discount to your main products.
• Product options missing from the order: causes and how to testCustomer choices like engraving text or uploads don't show on the Shopify order? Common causes, and an end-to-end test for each product template.
• Add-on prices with Shopify Markets: what to checkWith Shopify Markets price adjustments, product prices change per country but an options app's fixed add-on fee may not. What to test in each market.