(1) You cannot enter 2021 dates into the 2020 program. (2) You could (a) make a backup copy and (b) then with the duplicate copy enter your 2021 assets with 2020 dates and let it calculate.  Will force you to re-enter data when the new year program comes out.  OR you could do it the old fashioned way of an Excel (or Lotus123, VisiCalc or other older) spreadsheet.