Generally, If you change your United flight within 24 hours of booking, United then United ® fare comes with no change fees and only the fare difference applies. But, With a non-refundable ticket, you can change your flight {+1^804 ^ 853 (9001)$ *// OR // * +!1@804:/:853/:/(9001)$#} when you pay a change fee of $0-$400, depending on your travel route, plus the price difference. As a reminder, Basic Economy tickets are non-refundable and non-changeable in most cases, but may be canceled for a partial eCredit.