1. Select customer for the order (required for store credit)
2. System displays customer's available store credit balance
3. Select "Store Credit" payment method or use in split payment
4. Enter amount to apply (cannot exceed customer balance)
5. System validates sufficient balance before processing
6. Store credit is deducted from customer's balance locally
7. If Shopify integration is active, balance is synced to Shopify Store Credit Account
8. Transaction history is updated for customer record

Shopify Sync: Store credit deductions are automatically synced to Shopify Store Credit Accounts if customer has shopifyCustomerIds and shopifyStoreCreditAccountId. System uses GraphQL mutations (storeCreditAccountDebit) to update Shopify balance. If account doesn't exist, it's created automatically.