Instead of inserting column breaks, insert an empty paragraph at the end of your document, select the last paragraph break in your document and format the layout there for a single-column page. Word will insert a continuous section break there, balancing the columns. You can then hide the last paragraph's font and/or reduce the last paragraph's before/after spacing to 0, its point size to 1 and its line spacing to a 0.1 multiple.

That should avoid any spill-over to a new page if your last 'real' page fills up.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]