The Internal Revenue Service places restrictions on how far back you can amend your tax return, regardless of whether you owed tax or received a refund. Filers must use Form 1040X to amend a return and should only file an amendment to report certain changes. You have three years from the due date of the original return or two years from when you paid tax owing to submit an amended return.
What To Report
The IRS does not require an amendment if you want to correct math errors or if you have forgotten to attach certain schedules. The agency will redo the math and send you a note if it requires missing forms. Amendments are necessary if you want to report changes in your status, income, deductions or credits.
How Much Time You Have To File
The three years starts when you were required to file your return. If you filed early, time does not start until the actual due date, usually around April 15. If you received an extension to file, time starts with the extended due date. If you owed tax, your amended return is due two years after you paid the tax or three years from the original return due date, whichever is later.