EVA cancellation policy varies depending on the route and the type of ticket. However, there is a general 24-hour cancellation policy for flights to and from the United States. This means that you can cancel your flight without a penalty if you do so within 24 hours of purchase and if you booked your ticket at least one week (168 hours) before the departure date.
If you cancel your flight after 24 hours of purchase, you will be subject to a cancellation fee. The amount of the fee will depend on the type of ticket you purchased and the date of cancellation. For example, if you cancel a non-refundable ticket within 7 days of the departure date, you will be charged a cancellation fee of USD$200.