The IRS never gives you a final, absolute approval of your tax return. They may process it and send you your refund, but they can still go back later and take another look at your return. They have three years to raise questions about your tax return and tell you to pay additional tax. After three years from the date that you filed or the filing deadline, whichever is later, you can be pretty sure that your tax return is approved. They can only go back more than three years in cases of major underreporting of income or fraud.
