txtCalDue.controlSource = DateAdd("yyyy",1,txtDate)
Saving calculated data (data dependent on other data) to table is not always necessary and can even be very bad design.
If the next calibration due date is always +1 year, in textbox ControlSource property: =DateAdd("yyyy",1,CalDate).
If you really must save calculated value, then code could go in the AfterUpdate event of the user input textbox:
Me.CalDueDate = DateAdd("yyyy", 1, Me.CalDate)
If you don't want to allow user to change this value then set CalDueDate textbox as Locked Yes, TabStop No.
Date is a reserved word, should not use reserved words as names for anything. Advise no spaces or punctuation/special characters (underscore only exception) in names.
How to attach file: http://www.accessforums.net/showthread.php?t=70301 To provide db: copy, remove confidential data, run compact & repair, zip w/Windows Compression.