Office filing cabinets are deceptively dangerous when loaded, since a full cabinet can weigh several hundred pounds and has tipped more than a few dollies. Empty every drawer first and the rest is routine furniture moving.
Pro tip: Transfer files in their existing folder order directly into moving boxes labeled by drawer, which turns refiling at the new office into a simple reverse of the packing process.
Watch out: Never move a filing cabinet with drawers still loaded; a full multi-drawer cabinet can weigh several hundred pounds and has caused serious back injuries and tipped dollies when moved loaded.