The IRS has three years from the due date of the tax return to audit and adjust a tax return. A taxpayer can amend a tax return for three years. The due date for your 2014 tax return was April 15, 2015. Even if you file a return on March 1, 2015, the IRS has until April 15, 2018 to audit the return. You have until April 15, 2018 to amend the return. If you extend the due date of the return, the period of time the IRS has to audit and the period of time you have to amend the return is also extended. Your supporting documents should be kept for seven years, but your tax return should be kept permanently.