Gutter Property
Returns or sets the amount (in points) of extra margin space added to each page in a document or section for binding. Read/write Single.
Remarks
If the MirrorMargins property is set to True, the Gutter property adds the extra space to the inside margins. Otherwise, the extra space is added to the left margin.
Example
This example adds 1 inch (72 points) to the inside margins of the active document.
With ActiveDocument.PageSetup
.MirrorMargins = True
.Gutter = 72
End With