POS 11.5 Updates Fixed‑Amount Line Item Discount Calculation
POS now applies fixed‑amount discounts per unit; rounding may add up to one cent, but no action is needed for API 2026‑04 or earlier.
No action required now; monitor future API releases for per‑unit discount requirement.
Summary
Starting with POS version 11.5, Shopify has changed the internal calculation for fixed‑amount line item discounts to apply on a per‑unit basis instead of across the entire line item. This change only affects FixedAmount discounts; percentage discounts remain unchanged. When the total discount amount does not divide evenly by the quantity, the system rounds up, potentially increasing the total by up to one cent—for example, a $5.00 discount on three items becomes $1.67 per unit, totaling $5.01. Extensions using setLineItemDiscount or bulkSetLineItemDiscounts can continue to pass the total discount amount as before; the POS system handles the conversion automatically. No action is required for extensions using API version 2026‑04 or earlier. In a future API version, extensions will need to pass per‑unit discount amounts directly, and additional details will be provided closer to release.
This update ensures more accurate per‑unit discount application while maintaining backward compatibility for current API consumers.
Key changes
- Fixed‑amount line item discounts are now calculated per unit instead of per line.
- Percentage discounts remain unchanged.
- When the discount amount does not divide evenly by quantity, rounding may increase the total by up to one cent.
- Current API (2026‑04 or earlier) accepts the total discount amount; POS handles conversion automatically.
- Future API versions will require per‑unit discount amounts to be passed directly.
- No immediate action required for extensions using the current API version.
- Example: $5.00 discount on 3 items becomes $1.67 per unit, totaling $5.01.