You can use the navigation control selectedtab properties: caption or name. Name is probably cryptic value; caption probably more intuitive to you.
Forms![navigation form].NavigationControl0.SelectedTab.Caption
assumes you kept the default name for the nav form (navigation form) and default for control, which may or may not end in 0. Then when same form opens, get this property and do a select case, one case for every tab.
The more we hear silence, the more we begin to think about our value in this universe.
Paraphrase of Professor Brian Cox.