For tapes that you want to take monthly and put in a box, perform an
archive of those files and give them a retention period of 12 months.
Thus after 12 months they will no longer be tracked.  You can use this
and the daily backups together to provide what you want.

To explicitly get separate tapes for this archive data, you may need
to setup a separate set of storage pools for this.  Once the run is
done, mark all tapes as read-only so the next monthly run will create new
tapes.

Paul