I have paper for the current year, plus the prior two.

I have PDF's for at LEAST 7 years.

I have scanned copies of organizer/workpapers/tax return for at LEAST 7 years.

Three year old stuff gets shredded annually ( we try to make a party out of it... 🙂

Yep, I'm old.

TWICE having "old, really old" stuff in paper or scanned format has been very beneficial to folks in a divorce.