Currently, all changes and cancellations to award flights booked via Alaska Mileage Plan are free, until 60 days prior to departure. This allows you to secure a seat even if you do not have firm plans for your trip. Any change or cancellation within 60 days of departure will incur a charge of US$125.
From 5 Jun 2018, the fee of US$125 will be charged for any change or cancellation made after you have secured your award seat. In any case, this shouldn’t deter you from making use of excellent redemption opportunities, such as the one-way stopover trick which can get you an ‘almost’ full return trip to Japan in JAL Business Class from Singapore for 25000 miles.