Sometime late last year, Singapore Airlines announced the changes (that are already in effect at the time of writing) to the mileage accrual rates, seat selection as well as baggage allowances. One of the things mentioned then was the upcoming changes to the fees pertaining to award tickets as well as redemption upgrades on Singapore Airlines, SilkAir and other partner airlines that will come into effect on 01 March 2018.
Singapore Airlines currently has one of the most generous policies when it comes to service fees that relate to award tickets as well as redemption upgrades. There are no fees involved in changing the dates on Singapore Airlines and SilkAir flights (as long as it is confirmed award ticket) and a redeposit of miles for complete unused tickets costs only USD 30 (USD 15 if you hold elite status with the KrisFlyer program!).
As of 01 March 2018 however, changing dates on a Singapore Airlines or SilkAir award flight may cost you US$25 regardless of your status level with the KrisFlyer program - this charge is waived if you redeem an Advantage award ticket instead of a Saver one. Redepositing your miles will no longer cost US$15 or US$30 but it will cost you either US$70 (for Saver award tickets) or US$50 (for Advantage award tickets) instead.
The good news is this - if you have an upcoming flight planned and you have yet to redeem for it, the best time to do it (keeping the upcoming changes in mind) is now. According to the FAQ published by Singapore Airlines, all award tickets issued before 01 March 2018 are subject to the old change fees for the first time the ticket is changed - do note that the new fees will apply on subsequent changes (or cancellations thereafter). All tickets that are issued on or after 01 March 2018 will be subjected to the newer (and more costly) service fees.