If you have not filed a previous year tax return and you think you are due a refund, you better get going! There is a statute of limitations of three years from the date the taxs return is due to claim a refund. After that it expires and you are not entitled to it anymore. On the other hand, if there is tax due, the IRS can demand payment on a return until three years after it is due or three years from when it is filed, whichever is later. So if you haven’t filed the IRS can collect on it forever (Theoretically of course.)