Timebased Workflow for x period of time from expiration date

I am currently trying to create a workflow that will send out a notification 365 days prior to an expiration date as a reminder.  I tried to put the following in the Until When Date Time Expression.  I have also tried putting this in the How Long Expression as well.  We need these reminders to go out 365 day prior to expiration, 270 days prior, 180, 90, 60, 30...

[<dExpiration_Date_ITAG>] - Duration('P1Y')