Code to stop vba from overwriting content of Offset cell

I have an event macro that puts data into columns AB&C if criteria in N matches requirement. I need to prevent that code from running if the cell in column b already contains data

Dim rng As Range
If Intersect(Target, Range("N:N")) Is Nothing Then Exit Sub
If Target.Count > 1 Then Exit Sub
Application.ScreenUpdating = False
Application.EnableEvents = False
If Target.Value = "Completed" Or Target.Value = "Committed" Or Target.Value = "Cancelled" Then
With Target.Offset(0, -12)
  .Formula = Now
  .NumberFormat = "yy "
End With
With Target.Offset(0, -13)
  .Value = "TEAA"
End With
With Target.Offset(0, -11)
  .Value = ActiveCell.Row - 1
End With
End If
Application.EnableEvents = True
Application.ScreenUpdating = True
End Sub

Thanks

@nathansav

may be -12 and use code tags for code posting?

Thanks Excelliot, quick and so simple a solution, if you know how
Thanks

Cheers!!