Discount Combinations is the Rebuy setting that lets a Rebuy product discount and one of your own Shopify product discounts both apply to the same item in a cart. Use this article to turn discount stacking on, tag the Shopify discounts you want stacked, confirm the setting reached Shopify, and work out why a discount is still not stacking.
Putting two product discounts on the same item requires Shopify Plus, and that limit comes from Shopify rather than from Rebuy. Combining discounts of different types, such as a product discount with an order-level or shipping discount, is a separate Shopify feature that works on any plan when both discounts are set to combine.
What discount stacking on the same item does
Discount stacking lets a Rebuy product discount and one of your own Shopify product discounts, whether that discount is a discount code or an automatic discount, both come off the same line item on a Shopify Plus store, instead of Shopify keeping only the larger of the two. Without it, and on every plan below Plus, a product that qualifies for a store sale and for a Rebuy product discount at the same time gives the customer only one of the two, whichever is larger, no matter which Rebuy widget created the discount.
Stacked discounts do not add up to their combined percentage. Shopify applies them one after the other, taking whichever discount is worth the most money off the item's full price first, then applying the next one to what is left and rounding at each step. That order is the same for every Rebuy product discount, whatever Rebuy feature creates it.
Here is how that works out on a $100.00 item that qualifies for a 20% store sale and a 10% Rebuy product discount:
The 20% store sale takes $20.00 off the $100.00 price, leaving $80.00.
The 10% Rebuy product discount takes $8.00 off that $80.00, leaving $72.00.
The customer pays $72.00 and saves $28.00. Adding the percentages together would suggest $30.00 off, so expect a stacked total that is slightly smaller than the sum of the two discounts.
How order-level discounts fit in
Order-level discounts are unaffected by discount stacking and keep applying on top of whatever lands on the line items. Shopify treats a discount that comes off the order total as a different class from a product discount, and the two classes combine through Shopify's ordinary combination settings on any plan, including plans below Shopify Plus. Discount stacking only decides whether two product discounts can share one line item.
Continuing the $100.00 item above, with a 20% order discount code also applied to the cart:
The store sale and the Rebuy product discount leave the line item at $72.00.
The 20% order discount takes $14.40 off that $72.00 subtotal.
The order total is $57.60 and the customer saves $42.40 across the three discounts.
Rebuy's own order-level discounts work the same way. A Tiered Progress Bar order reward tier comes from a separate Rebuy discount that this setting never tags, and it combines with product discounts on any plan.
Turn on discount stacking in Rebuy
Enable discount stacking is the shop-wide switch that tags every Rebuy product discount so your own discounts can combine with it. It is off until you turn it on, and turning it on does not stack anything on its own until you also tag your own discounts in Shopify admin.
Stacking is all or nothing on the Rebuy side, so the toggle enrolls every Rebuy product discount at once. You set the scope yourself in Shopify admin by tagging only the discounts you want stacked.
In the Rebuy admin, select Settings in the left sidebar.
Select Discount Combinations.
Turn on Enable discount stacking. Rebuy tags every Rebuy product discount with
rebuyand allows that same tag on each one.Confirm the Current Shopify state table shows
rebuyin both the Tags column and the Combines with discounts tagged column for every row.
If a row still shows no tags after the page finishes saving, reload the page. If it still shows no tags, turn Enable discount stacking off and on again, or select Fix now if the page shows a sync warning.
Tag the Shopify discounts you want to stack
Tagging your own discounts is the half of the setup you do in Shopify admin, and Rebuy cannot do it for you, because Shopify stacks two product discounts on one item only when each discount names a tag the other allows. Rebuy handles its own side when you turn the toggle on, and you handle yours by tagging the specific discounts that should stack.
Repeat the following for each Shopify discount you want to stack with Rebuy:
In Shopify admin, open Discounts and select the automatic discount or discount code you want to stack.
Under Tags, add the tag
rebuy. Use COPY TAG on Rebuy's Discount Combinations page so the tag matches exactly.Under Combinations, in Product discounts, choose Multiple per product, then add
rebuyunder Combine on same product with discounts tagged.Save the discount, then test with a cleared cart on a product that qualifies for both discounts.
Only the discounts you tag stack with Rebuy. A discount you leave untagged keeps the combination settings it already has, so you can turn stacking on shop-wide and still opt in one sale at a time.
Shopify owns the combination rules and the resulting math, and Rebuy's setting only enrolls Rebuy's discounts in them. Shopify's Combining discounts guide is the reference for how the combinations themselves work.
Read the Current Shopify state table
The Current Shopify state table on the Discount Combinations page reports what Shopify holds for each Rebuy product discount, so you can confirm the toggle reached Shopify rather than trusting the toggle position. The table lists each Rebuy discount with its Shopify discount ID, the tags Shopify currently holds on it, and the tags it will combine with on the same item.
Column | What it tells you |
Rebuy discount | The Rebuy discount's name in Shopify, with its Shopify discount ID below the name. |
Tags | The tags Shopify currently holds on that discount. A value of |
Combines with discounts tagged | The tags this Rebuy discount will stack with on the same item. It contains |
With stacking enabled, every row carries rebuy in both tag columns. A row showing no tags in either column is not stacking. A table where some rows carry the tag and others do not means your Rebuy discounts have drifted out of sync, and the page reports that with a warning and a Fix now button that re-runs the tagging.
What turning on stacking does not affect
Turning on discount stacking is safe to do shop-wide, because it changes only whether two product discounts can land on the same item. The following work the same whether stacking is on or off:
Order-level Rebuy discounts. Rebuy's Order Discount is never tagged and this setting does not touch it. An order-level discount and a product discount already apply together through Shopify's ordinary combination settings.
Product discounts on different products. A product discount marked combinable in Shopify already stacks with another product discount targeting a different product, and it continues to.
Your own Shopify discounts that you do not tag. Turning stacking on does not alter any discount in your Shopify admin. A discount without the
rebuytag keeps the combination settings it already has, and it still cannot share an item with a Rebuy discount until you tag it.Shopify's cap on automatic discounts. Rebuy's discounts still count toward Shopify's maximum of 25 active automatic discounts.
Turn discount stacking back off
Turning Enable discount stacking off clears the rebuy tag and the allowed-tag list from every Rebuy product discount, so Rebuy discounts stop sharing an item with another product discount and go back to being the only discount on an item. Your Rebuy discounts keep working, and only their ability to stack goes away.
Your own Shopify discounts keep the tags you gave them in Shopify admin, so turning stacking on again restores the earlier behavior without retagging them.
Fix a discount that is not stacking
Work through the following when a Rebuy discount and one of your own discounts still give the customer only one discount on an item.
Confirm the store is on Shopify Plus. Shopify stacks two product discounts on one item only for Plus stores. On any other plan the Discount Combinations page still opens, but an Available on Shopify Plus warning sits at the top saying your current plan cannot apply these settings, and the Enable discount stacking toggle is greyed out. A development store does not count as Plus for this setting even if other Rebuy features treat it as Plus.
Confirm both tag columns show
rebuy. Check the Current Shopify state table. If a row shows no tags, turn the toggle on again, or select Fix now when the page shows a sync warning.Confirm your own discount is tagged and allows the tag. Your discount needs the tag
rebuy, and its Product discounts setting under Combinations needs to be Multiple per product allowingrebuy. Tagging one side is not enough, because Shopify requires the match in both directions.Check the tag count on your own discount. Shopify allows a maximum of 5 tags per discount, so a discount already carrying 5 has no room for
rebuyuntil you remove one.Confirm the Rebuy discount is a product discount. This setting only puts two product discounts on one line item, so a Tiered Progress Bar order reward tier is out of scope for it, and so is a Bundle Builder bundle whose Discount Mechanism is set to Cart Transforms. An order reward tier that is not appearing at all is a different problem, since it combines with product discounts on any plan without this setting. Switching a Cart Transforms bundle's Discount Mechanism to Shopify Functions makes its discount eligible to share a line item.
Look for a needs recreation flag on the Rebuy discount. Rebuy discounts created before February 5th, 2026 can carry a discount class that Shopify silently refuses to stack, and re-applying tags cannot repair it, which is why Fix now does not clear this flag. A discount carrying this flag has to be recreated before it can stack on the same item. Contact Rebuy Support to confirm whether a flagged discount is affected and how to have it recreated.
Discount stacking limitations
Discount stacking has boundaries that no setting in Rebuy or in Shopify admin works around. Check the following before you build a promotion that depends on two discounts landing on one item.
Shopify Plus is required. Shopify offers same-item product discount stacking to Plus stores only. On any other plan a Rebuy product discount and one of your own product discounts on the same item still give the customer only the larger of the two.
Product discounts only. Stacking reaches any Rebuy discount that comes off an item's price through Rebuy's Shopify Functions product discount, whichever widget creates it. A Rebuy discount that comes off the order total is a different class of discount and cannot be one of the two discounts on a line item, which is what puts Tiered Progress Bar order reward tiers and Bundle Builder bundles priced through Cart Transforms outside this setting. Those keep combining with your own discounts through Shopify's ordinary combination settings on any plan, and this setting neither helps nor hinders them.
Enrollment is shop-wide. Rebuy has no per-widget or per-discount control, so stacking is either on for every Rebuy product discount or off for all of them. Choosing which of your own Shopify discounts carry the tag is the only way to narrow the scope.
The shared tag is always
rebuy. Rebuy has no editor for setting a different shared tag, so both sides of every stacking pair userebuyexactly as the Discount Combinations page shows it.Shopify allows a maximum of 5 tags per discount. A discount already carrying 5 tags has no room for
rebuyuntil you remove one, and the cap applies to your own discounts as much as to Rebuy's.Some Rebuy discounts created before February 5th, 2026 cannot stack until they are recreated. They carry a discount class Shopify refuses to stack, and re-applying tags does not repair it. Rebuy flags these on the Discount Combinations page. Contact Rebuy Support about any discount carrying the flag.
Frequently asked questions
Can Rebuy's Shopify Functions discounts stack with Shopify's multiple product discounts on a single cart line behavior?
Yes, Rebuy's Shopify Functions discounts stack with Shopify's multiple product discounts on a single cart line behavior once you turn on Enable discount stacking on the Discount Combinations page. Rebuy previously could not add the discount tags that Shopify's same-line stacking depends on, so Rebuy's discounts could not take part in it. Rebuy now tags every Rebuy product discount rebuy and allows that tag, which completes Rebuy's half of the reciprocal tag match Shopify requires. Shopify offers this behavior to Plus stores only.
Why is only the larger discount applying when my store sale and my Rebuy discount hit the same product?
Only the larger discount applies when your store sale and your Rebuy discount hit the same product because same-item stacking has not been set up on both sides yet. Shopify gives the customer one product discount per item unless each discount names a tag the other allows, and it keeps the larger one. Turn on Enable discount stacking in Rebuy, then tag your sale rebuy in Shopify admin and set its Product discounts combination to Multiple per product allowing rebuy. If your store is not on Shopify Plus, Shopify does not offer same-item stacking at all, so a store sale and a Rebuy discount that hit one product always give the customer only the larger of the two.
What happens on a store that is not on Shopify Plus?
On a store that is not on Shopify Plus, discount stacking cannot be turned on, and a Rebuy product discount and one of your own product discounts on the same item still give the customer only the larger of the two. The Discount Combinations page opens in the Rebuy admin on any plan, but an Available on Shopify Plus warning sits at the top, and both the Enable discount stacking toggle and the Current Shopify state table are disabled, so no tags can be applied. This is a Shopify platform limit rather than a Rebuy one, since Shopify offers same-item product discount stacking to Plus stores only. A development store does not count as Plus for this setting even if other Rebuy features treat it as Plus.
Without Shopify Plus, structure promotions so that only one product discount targets any given product. An order-level discount and a product discount are a separate case and still combine through Shopify's ordinary combination settings on any plan, so a Tiered Progress Bar order reward tier and a product discount can both apply without Plus.
