Too long, I guess. When we built on my office addition, we put a basement under it which makes a fine, safe storage room. However, I make external backups every single year so could always reprint the return if I had too. But, that doesn't cover the notes, forms attached, etc; so I am thinking of starting to burn more since we have an outside wood burner. On the other hand, there have been a few instances when we have had to dig way back. As you said, sometimes they leave and come back several years later. I just had one last year that hadn't been here for 9 years because I fired her. She came back asking nicely and so far all is well. I am going to say seven to 10 years because I have the room and I can just see so many of you throwing up your hands in horror. That's what happens when you started out with pencils, erasers and printed forms and a copy machine.