addding a year to a date

christopher_Eade 

You added Excel for Web as tag. VBA macros don't work there, only in the desktop version of Excel for Windows/Mac.

You could do the following on Windows/Mac:

Right-click the sheet tab.

Select 'View Code' from the context menu.

Copy the code listed below into the worksheet module.

Switch back to Excel.

Save the workbook as a macro-enabled workbook (*.xlsm).

Make sure that you allow macros when you open it.

Private Sub Worksheet_Change(ByVal Target As Range)
    If Not Intersect(Range("A1"), Target) Is Nothing Then
        If IsDate(Range("A1").Value) Then
            Application.EnableEvents = False
            Range("A1").Value = DateAdd("yyyy", 1, Range("A1").Value)
            Application.EnableEvents = True
        End If
    End If
End Sub