Did you miss a credit or deduction, or need to correct something else on your tax return for this year or past years? If so, you can file an amended tax return.

Here are five things you need to know about amending a tax return:

First, be sure to identify the year of the return you’re amending. Remember, normally you can only go back three years.

Second, choose how you want to file your amended return. Returns for tax year 2019 or later can be amended electronically. If you’re amending a return prior to 2019, you’ll need to mail the paper Form 1040-X to the IRS.

Third, if you’re amending more than one return, you must prepare a separate 1040-X for each year. If you mail these Forms 1040-X to the IRS, use separate envelopes, and be sure to send them to the correct IRS address depending on where you live. You can find this information in the form’s instructions.

Fourth, if you’re filing for an additional refund, wait until you get your original refund before filing a 1040-X.

Finally, don’t amend your return just because of math errors. We’ll check your math and fix the error for you.

You can learn more at IRS.gov/1040X.