expression.ColumnSpacing
expression Required. An expression that returns one of the objects in the Applies To list.
Remarks
Spacing measures from the end of the text to the end of the column and again from the beginning of the column to the beginning of the text. Thus, if you enter a ColumnSpacing amount of 0.5, the total spacing between columns will be one inch: half an inch measuring from the end of the text to the end of the column in one column, and half an inch measuring from the beginning of the column to the beginning of the text in a neighboring column.
Example
This example formats the first text box in the active publication with three columns and a total of half an inch spacing between columns.
Sub SetColumnsAndSpacing()
With ActiveDocument.Pages(1).Shapes(1).TextFrame
.Columns = 3
.ColumnSpacing = InchesToPoints(0.25)
End With
End Sub