Tax season is over, and what a relief! But what do you do with all of this paperwork? For years, the rule of thumb for individual tax filers has been to keep federal tax returns and all supporting documents for three full years. This is based on the principle that the IRS can audit your last three returns only if they believe that you made a good-faith error. However, be aware that the IRS can audit your returns for up to six years if they suspect that your income was misrepresented on any tax return by 25% or more. Therefore, to be completely safe, keep tax returns and supporting documents for seven years before shredding them. In addition, it's a good idea to keep a permanent copy of all 1040 forms from each year's return in one file.