Try electronic filing, it's wonderful! We use UltraTax for tax filings and store the returns, original tax docs, signatures etc in their electronic "file cabinet." We can also send what we prepare in ATX like 1099s and W2s to there, as well as correspondence, sales tax returns, notes, IRS letters, you name it. You can achieve the same thing by saving files prepared in the tax program to specific client files you create and scanning signature docs or whatever and saving them to there as well. It is so easy to sit at your desk and pull up the client files while they are on the phone. They need copies of their W2s for the last two years? Right there. You don't even have to print them, just fax or email right from your desk. And you don't have to dig out paper files, find what you want, and they put the files back in the right place in the physical file cabinet (we were never good at that part). The only paper files we keep now are Forms 2848 with original signatures. I also keep tax docs for estates because they are often reported for a calendar year and since most of my estate tax filings are for fiscal years, it is just easier to have the paperwork where I broke down what belongs to the decedent and what goes to the estate, and which fiscal year gets what.
I highly recommend that you purchase or create some kind of electronic filing system that will work for you. This summer, hire a high school or college student to scan and file. Then call Shred It to come get the whole pile.
PS. We will not be switching to ATX for tax this coming season as we had planned. There are so many changes in the tax code that it will overwhelm us and staff to learn a new program and the new law simultaneously. Also, there is a little more confidence that UT will be at least a little better at getting the new programming right. It better for the $18k it costs.