Kirill Bondar 11/27/2013 2:35:13 PM
Unfortunately, duration can not be expressed in months in years precisely: 366 days is 1.0 year if the year is leap, and 1.03 years if it is not. The same is with months: 28 days is 1.0 month if it is February of non-leap year, and slightly less than 1 for all the other cases.
Given two dates, you can basically reach you goal with the following formula:
Format(YearsBetween([To], [From], "0")) & " years " & Format(Rem(MonthsBetween([To], [From]),12), "0") & " months"