CustomTab Property
True if the specified tab stop is a custom tab stop. Read-only Boolean.
Example
This example cycles through the collection of tab stops in the first paragraph in the active document, and left-aligns any custom tab stops that it finds.
Dim tsLoop As TabStop
For each tsLoop in ActiveDocument.Paragraphs(1).TabStops
If tsLoop.CustomTab = True Then
tsLoop.Alignment = wdAlignTabLeft
End If
Next tsLoop