diff --git a/src/app/api/checkout/route.ts b/src/app/api/checkout/route.ts
index c758652..427878f 100644
--- a/src/app/api/checkout/route.ts
+++ b/src/app/api/checkout/route.ts
@@ -75,10 +75,14 @@ export async function POST(req: Request) {
     }
 
     const activePromotions = await fetchActivePromotions();
-    const pricedItems = items.map((i) => ({
-      ...i,
-      unitPrice: getEffectivePrice(productsById.get(i.productId)!, activePromotions).price,
-    }));
+    const pricedItems = items.map((i) => {
+      const design = i.designJson as { front: unknown[]; back: unknown[] };
+      const isPersonalised = design.front.length > 0 || design.back.length > 0;
+      return {
+        ...i,
+        unitPrice: getEffectivePrice(productsById.get(i.productId)!, activePromotions, new Date(), isPersonalised).price,
+      };
+    });
 
     const total = pricedItems.reduce((sum, i) => sum + i.unitPrice * i.quantity, 0);
     const customer = await getCurrentCustomer();