Controlled discounts on sale items

The sale-items lock is all-or-nothing: past your threshold, the code dies. That’s right for many stores — but it costs you the customer who abandons when their code “doesn’t work.” There’s a middle path: let codes work on sale items, at a rate you chose. Full-price items get the real discount; marked-down items get a token one. The double-dip becomes a controlled, priced-in dip.

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 kind of item.

The setup

Everything happens inside one PromoLock discount, using cart groups’ Sale status filter — no collections, no product tagging, no maintenance. An item counts as “on sale” when its price is below its compare-at price, and the groups sort the cart automatically at checkout.

1. In Discounts, create your discount (code or automatic).
2. The step everyone misses: in the right rail under Margin guards, set On-sale items to Shopify default. It ships as No discount, and while it’s on that setting, sale items are dropped before your offer ever sees them — the Sale status filter doesn’t even appear in the group editor, because it would do nothing. (Not Sale or code: that option nets the code against the markdown, so your 5% would usually come out to $0.)
3. Open the group manager (Create/Manage groups from any product discount) and create two groups:
   • Group Full-price items: turn on Filters → tick Sale status → Only full-price items.
   • Group Sale items: same, but Only items on sale. Leave both groups’ catalog selection empty — the filter alone splits the whole cart cleanly, and every item lands in exactly one group.
4. In the offer, add two Product discounts: Percentage off 20 aimed at Full-price items, and Percentage off 5 aimed at Sale items.
5. Cap it: Cap total discount in Margin guards still applies across both rates — set it, and even a cart full of everything has a ceiling.

Because the split is computed from live prices at checkout, it maintains itself: mark a product down and it moves to the 5% side; restore the price and it moves back. Nothing to update, ever.

The one-setting version: Sale or code

If two groups and two rates is more policy than you want, the On-sale items guard has a middle option of its own: Sale or code — whichever saves more, not both. The code keeps working on sale items, but the markdown the sale already gave counts toward it, so a sale item only gets the part of the code that beats its sale. A 20% code on a $10 item marked down to $7 gives nothing extra (the sale was already worth more); a 50% code takes it to $5. Full-price items get the full 20% as usual.

The difference from the two-rate setup: Sale or code guarantees a sale item never costs you more than the code’s headline rate off the original price, while the two-rate discount pays a fixed, smaller rate on top of the sale. Pick Sale or code when the promise you want to keep is “20% off, full stop”; pick the two rates when you want sale items to always get something for the code.

Retire the blunt instruments for this policy

• Don’t run the Controller’s Lock Discount Usage On Sale Items alongside this — that lock blocks all codes on sale-heavy carts, including your two-rate one. This strategy replaces the lock; pick one policy or the other.
• Old ungoverned codes should be retired or blocked so the two-rate discount is the path customers actually take.

Choosing between the two policies

Situation	Better policy
Sale prices are final — codes shouldn’t touch them, full stop	Sale-items lock
Codes are part of your brand and blocking them costs conversions	Two-rate discount (this page)
Deep clearance where even 5% hurts	Keep the lock — or set the sale-side rate to a symbolic 1–2%

What to watch

After a few weeks, open Analytics → Sale-item discounts. Loss on sale items won’t be zero under this policy — that’s the point, the 5% is planned — but the line should be small, flat, and boring. If it climbs, some other code is reaching sale items ungoverned; the top-discounts list will name it.

Pitfalls

• Leaving On-sale items on No discount. The symptom: sale items get no discount at all, the Sale status filter is nowhere to be found, and support tickets say “code doesn’t work.”
• Only creating the sale-items group. Without the full-price group’s filter, the 20% side would target the whole cart — sale items included. Two filtered groups, one rate each, no overlap.
• Leaving other codes combinable. The two-rate discount prices in the dip — a second code stacking on top un-prices it. Keep the stacking lock on and this discount’s Combines with flags off.
• Stale compare-at prices. An item whose compare-at was left above its price after a “sale” ended still counts as on sale and gets the 5% rate. Clearing compare-at when a markdown ends keeps the split honest.