https://community.nicic.gov/node/43223
Do you have questions about flight change costs of United airlines? Well, United Airlines allows passengers to change flights up to 24 hours before their scheduled departure time, for free and with no penalties. After the 24-hour period, United Airlines Change Fees will be $200 to change the date and time of their flights. If your itinerary includes travel within the United States and Canada, there will be no United change flight fee. This does not apply to the Basic Economy fare. There is no longer a standby fee if you fly earlier on the same day.