The Internal Revenue Service offers a letter which verifies non-filing status to individuals who have to prove they didn't file an income tax return. As of 2015, the Verification of Non-filing Letter is only available online, using the Get Transcript of Your Tax Records link on the IRS homepage.
The individual requesting the letter must have a valid Social Security number and an email account to receive a confirmation code, according to IRS instructions. Items required to prove identity include name, date of birth, filing status and the most recent mailing address the IRS has on file. Other information, such as old addresses or loan information, may also be needed.
The verification letter is not available for the current filing year until after June 15. The letter also doesn't address whether the taxpayer should have or was required to file a tax return, warns the IRS.