Why coupons actually fail, according to 78 million promo code tests

One in four promo codes fail. But the reason isn't what most people assume.

Across 2024 and 2025, SimplyCodes ran 78.8 million live checkout tests across more than 500,000 retailers. The failure rate: 26.2%. Nearly 21 million codes were rejected at checkout — not in a lab, but in real purchase flows with real carts. These tests were done by expert verified coupon testers who know where to find coupons that work, know which ones they believe will work, and are experts on coupon restrictions.

Shoppers feel this acutely. Across 2024 and 2025, over 2.2 million user votes were cast on promo code listings on SimplyCodes. Nearly 9 in 10 — 87.6% — were downvotes, meaning the shopper reported the code didn't work. That number is inflated by selection bias (people are far more likely to vote when something fails than when it works), but it captures something real: for the average consumer, the coupon experience is overwhelmingly one of failure.

The obvious explanation is that most of those codes were expired, fake, or mistyped. The data tells a different story.

Over the last 30 days alone, SimplyCodes logged 240,974 restriction events — instances where a code was blocked at checkout by a specific rule. When we broke down the source of those restrictions, the split was decisive: 82% came from merchant-wide checkout rules, not from anything wrong with the code itself.

Most promo codes fail because of retailer rules, not the code itself

Merchant-wide restrictions are rules baked into a retailer's checkout system that apply to every promotion. They include minimum and maximum spend thresholds, payment method requirements, customer-type eligibility gates, and auto-applied discount conflicts. When one of these rules blocks a code, switching to a different code almost never helps — because the rule applies to all of them.

The most common restriction was minimum spend, with nearly 56,000 occurrences — 96% of which were merchant-wide. If a store requires a $75 subtotal and the cart is at $68, every code will fail. No amount of code-swapping changes that.

Payment method restrictions followed a similar pattern: 95% merchant-wide. Some discounts only activate with specific checkout methods — card only, no buy-now-pay-later — and the shopper has no indication this is happening.

Customer-type eligibility accounted for nearly 13,000 events, 85% merchant-wide. These rules silently limit codes to new customers, loyalty members, or logged-in accounts. If the shopper's status doesn't match, the code is dead on arrival.

The only major category where code-swapping actually helps is product and category exclusions — and even there, 86% of those restrictions are promo-specific, meaning they're attached to individual codes rather than the store's system. Switching codes can work, but only after the merchant-wide blockers are already cleared.

What to do when a promo code is rejected at checkout

The instinct when a promo code fails is to try another one. Then another. Then give up. That's exactly backward.

Because the vast majority of checkout restrictions are structural — applied at the store level, not the code level — rotating through codes without changing anything else is the lowest-probability strategy available. It's the equivalent of trying different keys on a door that's bolted shut.

The pattern that actually works looks more like this: figure out why the code failed before reaching for a new one. Is the cart below a spend threshold? Is a sale item in the cart triggering an exclusion? Is the wrong payment method selected? Is an auto-applied discount blocking stacking?

Small adjustments — adding a low-cost item to hit a threshold, removing one excluded product, switching payment methods, or logging out to test new-customer eligibility — resolve failures that no amount of code-hunting would fix.

Even under professional testing conditions, roughly one in four codes still fail. The difference isn't access to secret codes. It's knowing whether the problem is the code or the checkout system — and acting accordingly.

Methodology

This analysis draws on two primary datasets maintained by SimplyCodes: code verification tests and user-submitted vote data.

For the failure rate analysis, SimplyCodes conducted 78.8 million live checkout tests across more than 500,000 retailers over the course of 2024 and 2025. Each test was performed by an expert-verified coupon tester who attempted to apply a promo code during a real purchase flow with an active cart. Codes were classified as successful or failed based on whether the retailer's checkout system accepted the discount. The aggregate failure rate was calculated as the share of all tested codes that were rejected at checkout.

User sentiment data was collected from opt-in voting on promo code listings across the SimplyCodes platform during the same period. Users could submit an upvote or downvote to indicate whether a code worked for them. A total of 2.2 million votes were recorded. It is worth noting that this data carries inherent selection bias, as users are more likely to vote after a negative experience than a positive one.

For the restriction analysis, SimplyCodes logged individual restriction events over the most recent 30-day window. Each event captured the specific reason a code was blocked at checkout, along with whether the restriction was merchant-wide (applied uniformly across all promotions by the retailer's checkout system) or promo-specific (attached to an individual code). Restriction types were then categorized — including minimum spend, payment method, customer-type eligibility, and product or category exclusions — and the merchant-wide versus promo-specific split was calculated within each category.

All data reflects real checkout interactions and does not rely on self-reported surveys or simulated environments.