Delta Airlines allows passengers to receive a refund in certain circumstances. Refunds are available for tickets cancelled within 24 hours of purchase, non-refundable tickets under certain circumstances, cancelled flights, delayed flights over 90 minutes, and seat upgrades that cannot be provided. Refunds are typically processed within 7 business days, but may take up to 21 days to appear in your account. It is recommended to review the terms and conditions of your booking or contact customer service for more information on Delta's refund policy.