Shipping discount function
The legacy function for free-shipping rewards on stores that haven't migrated.
A legacy Shopify Function specifically for free-shipping rewards. It takes 100% off the shipping rate at checkout when conditions are met.
When it fires
Whenever a free-shipping reward tier is unlocked. The function reads the reward configuration, checks whether the cart qualifies (cart total or item count, depending on your Reward Basis), and makes shipping free if it does. On stores that haven't migrated it runs behind the IA Cart - Shipping Discount discount; on the unified discount the same free-shipping rewards run inside Oxify Cart Unified Discount.
Why a dedicated function
Shopify treats shipping discounts as a separate category from product / order discounts. Having a shipping-specific discount ensures the reduction is applied to the shipping rate specifically — not the order subtotal.
Combinations
On the unified discount, whether free shipping combines with other shipping discounts is controlled by Combine with other Shipping discounts in Cart Editor → Settings → Discount Settings (on by default). A discount code also has to allow it: check its Combinations section in Shopify admin → Discounts.
Auto-managed
Like the order discount function, this is managed automatically whenever you save the Cart Editor. No manual configuration needed.