An amended tax return is simply a revision of a previously filed return.
It’s not uncommon for a tax return to be filed only to realize that a mistake was made. Perhaps you had a net operating loss (NOL) that can be carried back to previous years. In some cases a credit or deduction was not taken. Sometimes you can call the IRS to straighten things out. In other cases the IRS makes a change to your federal tax return which then requires that your state tax return be amended.
Amended Tax Return Deadline
An amended return must be filed within 3 years of filing your original return, including extensions, or within 2 years of paying the original tax due (whichever is later).
An amended return that is filed with the IRS can take up to 3 weeks to be entered into their system and up to 16 weeks to be processed. You can check the status of your amended return on the IRS website. The IRS has been backlogged recently so processing may take longer than usual.