or, if there is already a tab immediately preceding the underlined text and you want to avoid duplicates use:
Code:
Sub ScratchMacro()
'A basic Word macro coded by Greg Maxey
Dim oRng As Range
Set oRng = ActiveDocument.Range
With oRng.Find
.Font.Underline = wdUnderlineSingle
While .Execute
If Not Asc(oRng.Characters.First.Previous) = 9 Then
oRng.InsertBefore vbTab
oRng.Collapse wdCollapseEnd
End If
Wend
End With
lbl_Exit:
Exit Sub
End Sub