How Promo Codes Work (and Why They Sometimes Fail)

A promo code is simply a text string that a store's checkout system matches against a list of active discount rules. When the code matches, the system applies whatever rule is attached to it, such as a percentage off or a fixed dollar amount.

Codes fail for a handful of predictable reasons: the code has expired, it's restricted to specific products, it requires a minimum order value, or it's a first-time-customer-only offer.

Retailers also frequently limit how many discount codes can be combined in a single order, so if a code doesn't apply, try removing any other codes already in your cart.

If a code still doesn't work, it's worth checking the coupon's terms or trying a different active code from the same store rather than assuming no discount is available.