Glad it worked.

(Disregard my last comment, I didn’t see you last post until I submitted mine).

Also, when does the error occur ?

In design mode (right click on the form and select ‘design View’), click on the [Recurrence] field and in the Property Sheet select the ‘event’ tab, then click on the “After Update” event and click on the “…” button to the right, and select “Code Builder”.

Write this code inside the Recurrence_AfterUpdate procedure created:

 [Due Date] = DateAdd("m", [Recurrence], [Date Completed])

Save your work.

This will calculate the due date every time you modify the Recurrence field in the form.

To make sure the calculation is performed only when valid data exists in both fields (date completed and recurrence) you can add some validations:

If [Date Completed] <> "" And [Recurrence] <> "" Then
    [Due Date] = DateAdd("m", [Recurrence], [Date Completed])
End If

You might want to add this same code to the AfterUpdate event of the ‘date completed’ field, so the due date is recalculated when any of these two fields is modified.

If you want to update it automatically when new records are added, then you will need to modify the entry form to do the calculation when some event occurs.

Let us know how and when you want to do it, and we might be able to provide more help.