Each tax season, go through your file and toss what's no longer needed. Keep tax returns indefinitely (or for at least seven years), but you can discard supporting documents, like phone bills, after six years, says David Wiesenberg, C.P.A., of Studio City, California.
Also keep information on assets indefinitely, even after disposing of them, the IRS advises. You'll need it for calculating property depreciation or profit or loss from stock or fund sales.
A scanner can be a paper-reducing miracle: Scan things like utility bills onto your hard drive, save them on a rewritable CD as backup, and pitch records you'll probably never need again (though not documents relating to assets; you may need the originals one day).