Blocking discount codes on sale items is the standard fix for the double-discount problem, and it works. But it has a cost nobody puts on a dashboard: the customer whose code “doesn’t work” at checkout, who was maybe going to spend $150, and who closes the tab instead.
If codes are part of how your brand sells, there’s a smarter shape for this. Don’t block the code on sale items. Shrink it.
All items 20% off. Sale items 5% off. One code.
The customer’s code always works. You just decided in advance what it’s worth on each side of the markdown line. The double-dip still happens, technically, but at a rate you priced in, and a rate you priced in is a plan rather than a leak.
Why this converts better than blocking
A rejected code feels like a broken promise, even when the fine print was on your side. A code that applies, but applies modestly to clearance items, feels like it worked. The customer sees a discount land; you see 5% instead of 20% on the lines that were already marked down 30%.
For stores where a big share of traffic arrives holding a code (from email, from an influencer, from a welcome popup), that difference is real revenue. The all-or-nothing lock trades those checkouts away for margin. The two-rate version keeps both.
How to build it in PromoLock
The whole thing lives inside one discount, using cart groups with a sale-status filter. No collections to maintain, no product tagging. The split happens live at checkout based on each item’s price versus its compare-at price.
- Create your discount in PromoLock (code or automatic).
- Open SafeGuards and untick Skip on-sale items. This matters: it’s on by default, and while it’s on, sale items are removed before your offer ever sees them, so a sale-item rate would have nothing to apply to. The sale-status filter doesn’t even appear until this is off.
- Create two cart groups. Group one, call it
Full-price items: turn on Filters, tick Sale status, choose Only full-price items. Group two,Sale items: same filter, Only items on sale. Leave the catalog pickers empty on both. The filter alone splits the entire cart, and every item lands in exactly one group. - In the offer, add two product discounts: 20% aimed at
Full-price items, 5% aimed atSale items. - Set Cap total discount amount so even a giant mixed cart has a ceiling.
Because the groups are computed from live prices, the setup maintains itself. Mark a product down tomorrow and it moves to the 5% side on its own. Restore the price and it moves back.
One thing to switch off
If you’ve been running PromoLock’s sale-items lock in the Controller, turn it off before launching this. That lock blocks all codes on sale-heavy carts, including your carefully built two-rate one. The lock and the two-rate discount are two answers to the same question, so pick one.
And keep the stacking lock on. The two-rate discount prices in the dip; a second code stacked on top un-prices it.
Which stores should still just block
There is another side to this. If your sale prices are final-final, if you run deep clearance where even 5% on top hurts, or if codes are rare on your store anyway, the plain block is simpler and there’s nothing wrong with it. The two-rate structure earns its keep when code usage is high and checkout abandonment has a price.
What to watch afterwards
In PromoLock’s analytics, the sale-item loss report won’t go to zero under this policy, and that’s correct, because the 5% is planned spend now. What you want is a line that stays low and doesn’t trend anywhere. If it starts climbing, some other code is reaching your sale items ungoverned, and the report’s top-discounts list will tell you which one.