You can add tabs to a form programmatically, but the form must be open in
design view. It's generally better to create the maximum number of tabs you
will need at design time, and toggle their visibility at run time, which
does not require the form to be in design view.

Here's an example that gets the number of tabs and their captions from text
boxes on the form ...

Private Sub cmdBuildTabs_Click()

   Dim lngPages As Long
   Dim lngLoop As Long
   Dim varCaptions As Variant

   lngPages = CLng(Me.txtNumPages)
   varCaptions = Split(Me.txtTabNames, " ")

   For lngLoop = 0 To Me.tabTest.Pages.Count - 1
       Me.tabTest.Pages(lngLoop).Visible = False
   Next lngLoop
   For lngLoop = 0 To lngPages - 1
       Me.tabTest.Pages(lngLoop).Visible = True
       Me.tabTest.Pages(lngLoop).Caption = varCaptions(lngLoop)
   Next lngLoop

End Sub