In Workday Adaptive Planning formula syntax, [time=this.year-1] is the correct and officially supported modifier to retrieve the full prior fiscal year value of an account. This modifier navigates to the year period that is one year before the current year context, returning the annual total for the previous fiscal year --- which is the precise requirement for incorporating full-year prior year expenses into a formula. Option A uses [time=last.year], which is not standard Adaptive Planning formula syntax and would result in a formula error. Option C uses [year=previous], which is also not valid Adaptive Planning formula notation. Option D uses [time=this-12], which shifts back 12 months --- for a monthly formula, this returns the same month from the prior year, not the full prior year total. When a formula needs the full prior year annual amount (sum of all 12 prior months), [time=this.year-1] retrieves the aggregated annual value. This is the authoritative time modifier syntax for annual prior year references in Adaptive Planning. Reference: Workday Adaptive Planning --- Time Modifiers, Prior Year Reference, Formula Syntax Guide.