Be sure to identify the year of the return you’re amending at the top of the form. Normally, you can only go back three years.
Amended returns can only be submitted by mail, not electronically. If you are submitting more than one return, you must prepare a separate 1040x for each year. Make sure to use separate envelopes. Double check the address to make sure you are sending it to the correct IRS location depending on where you live.
If you are filing for an additional refund, wait until you get your original refund before filing the 1040x.
There is no need to amend your return because of math errors. The IRS will check it for you.
You can download the 1040x from opens in a new windowirs.gov.