It's probably the CUPS margins which are set wrong.  You can tell this if
the CUPS test page border is chopped anywhere.  Look in the files in:

     /etc/cups/ppd

There should be, for example, lp.ppd for your printer.  You should find a
section in there like:

    *DefaultImageableArea: Letter
    *ImageableArea Letter:  "8.60 39.60 603.40 766.49"

The numbers are in points (1/72").  The first two are the X,Y of the
lower-left-most printable pixel (i.e., X from the left, Y up from the
bottom); the second pair are X,Y size of the printable area.

You may have to fiddle with them a bit, print CUPS test pages to see what
happens.

I sure wish this were (1) correctly set by the installation, but it is
*very* printer dependent or (2) much easier to adjust with some kind of
tool.

\\/
http://www.wlindley.com