The Internal Revenue Service (IRS) has a 10 year statute of limitations for which they can collect back taxes. This means that the maximum period of time the IRS can legally collect on back taxes is 10 years. The 10 year period of time starts when the tax return is filed and the IRS posts it on their database. The IRS posts it on their computer six weeks after the tax return is filed. Thus, if the tax return is filed April 15, then the IRS will post it on their system by June 1.