It's been a very long time, but IIRC there's a longer statute of limitations for tax fraud than for inadvertent mistake. You still need to have six years' paperwork if you're audited (six tax years, which means the end of seven calendar years). Again, IIRC. Mr. S? Plus, federal taxes are one thing, but your statutes of limitations for contracts will vary state by state - those can go 15 years and maybe more.

A few years ago I was unable to claim several hundred dollars in a regulatory settlement with my insurance company because I hadn't kept the EOBs (and it would have required me to produce not only the EOBs, but also the prescription receipts, since the EOBs don't identify the drug they're reimbursing me for, only whether it's generic or brand name).

Storage lockers are relatively inexpensive if you need to get a few boxes of paper out of the house. A scanned image made by you is a handy reference when you need it, but it may not be possible to authenticate it as evidence, so originals are best.

Also keep medical records indefinitely. As a former Social Security claimants' representative, I've seen way too many cases where doctors' offices had closed and vanished with their records, VA records were lost in a fire, and claimants couldn't remember the names of their doctors from 20 years earlier.