- Short answer
- Partly: Shopify's one use per customer limit on a discount code tracks email or phone; in our test a guest with a new email used it again.
- Tracked by
- A customer's email address or phone number, per Shopify's setup steps
- Same email, second order
- Our dev-store guest test: code applied, then refused at Pay now ("has already been used"); no order
- Not tested
- Phone as the contact, Shop Pay, new customer accounts, POS
- Deleting the discount
- A duplicate with the same limit: past users of the old one can use the new one once
How does Shopify tell a customer already used the code?
Tick Limit to one use per customer under Maximum discount uses when you create a discount code.
- Discounts
- Create discount
Shopify names the key it tracks:
Check Limit to one per customer to limit the discount to one use per customer by tracking a customer's email address or phone number.
The limit belongs to that one discount: if you delete it and add a duplicate with the same limit, customers who used the old one can use the new one once.
Shopify's mobile steps for amount off and Buy X get Y codes add “This only applies to fixed value discounts”; their desktop steps don't. In our test, a 5% code made in the desktop admin kept the limit; we didn't test the mobile app, so create percentage codes on desktop.
What happens when a guest uses the code twice?
Our test, October 19, 2026: a 5% code with only this limit, online guest checkout in a development store, test payments, legacy customer accounts.
The same email saw the code applied, then was refused at Pay now: no order, and checkout said the code “has already been used” (what that message means).
A new email got the discount again, with the same name and shipping address. We didn't test phone as the contact, Shop Pay, new customer accounts or POS.
How do you keep a code to one use per person?
- Set Eligibility to Customer segments or Specific customers (up to 100 per code).
- A guest's new email has no customer profile, so it stays outside the segment until its first order is complete.
- A segment can't hold it: a first-time customer isn't in a segment until their first order is complete.
- Required sign-in narrows checkout to email, but with new customer accounts, signing in with an unknown email creates a new customer profile automatically; we didn't test whether required sign-in stops a second use.
- Discounts
- Create discount
Building a segment is shown in how to give employees a discount.
- Settings
- Checkout
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