Does Kia require you to change the transmission filter to maintain your warranty?

To be absolutely sure, I would call Kia, and ask them. Ask to speak to a service writer and when he/she tells you, write down his/her name and the date and time so yo will be covered. When I am ever in doubt about this type of stuff, I ALWAYS call the factory rep, i.e. the Dealership and get the info from the 'horse's mouth' so to speak.