Stacking rules and Shopify limits
Shopify's discount limits and combination rules — and how to work with them.
5 functions per cart
Shopify caps active functions at 5 per cart. The unified function counts as one slot, even though it's evaluating many discount types internally. Legacy installs with multiple per-type functions can hit the cap if you also use other discount apps — migrate to unified to free up slots.
Combinations
Configure combination rules in Shopify admin: Discounts → (your discount) → Combinations. The app honors whatever Shopify allows. Three combination types:
- Product discounts — Combine with other product discounts.
- Order discounts — Combine with order-level discounts.
- Shipping discounts — Combine with free-shipping discounts.
Order of application
Shopify decides the order, not the app. If two functions both reduce the same line, Shopify applies them in the order they were registered. The customer-facing total is correct regardless of order; the per-line attribution may shift.
Common pattern
Most stores end up with: unified discount function (Oxify) + 1 manual code (their own promo) + 1 Shop Pay protection function. That's 3 of 5 — plenty of room for additional rules.