A standard filing cabinet has a footprint of 26.5 x 26 inches -- that's 4.7847 square feet (actually, closer to six or seven square feet, when you allow for opening the drawers). Four drawers hold up to 19.1 cubic feet of stuff.
How many cabinets do you have? How many more do you need?
A nice four-drawer cabinet, built sturdily enough that you don't need to add a hanging file system, costs between $300 and $350, list. You can find them discounted to $160-$200. It holds a maximum of 19.1 cubic feet of materials ... and remember, it means you have to give up another 4.7847 square feet of invaluable office space.
What's a square foot of space worth in your office?
Mortgage/Rent divided by Square Footage
Guestimate ... and jot the figure down for future reference!
Jot down cabinets-need X $180, too.
How often do you use most of your documents?
Cash and charge receipts proving your honesty to IRS? Hopefully, never! You're required by statute to keep five years' worth of documentation in case of an audit; most companies keep at least seven years' worth, just to be safe.
How about payroll information -- contracts, time cards, pay stubs, health insurance forms, Worker's Compensation forms, Social Security data, 401(k) paperwork ... Or general accounting -- stock status reports (usually massive) ... Or client relations -- correspondence ... contracts ...
Probably (hopefully) the close of each fiscal year will end your immediate need to put your hands on any of this, but you could get into a situation where you need to go back to it even three or five years later.
Professionals who handle other people's records can be flooded with years of bulky materials. Doctors, dentists, and hospitals collect tons of medical records (including unwieldy X-rays). Accountants. Lawyers. They need to keep active records handy for two years. But inactive patients and clients' records? Older records? Most do not want to destroy them for up to seven years. Just in case ...
Start a list of the kinds of documents you're keeping, knowing/thinking/fearing you might need them some day ... but certainly not every day. Or month. Or even year.
Make a list. You'll be surprised!