The IRS offers these facts regarding amended tax returns.

1. Use Form 1040X, Amended U.S. Individual Income Tax Return, to correct errors on your tax return. You must file an amended return on paper- It can’t be e-filed.

2. You usually should file an amended tax return if you made an error claiming your filing status, income, deductions or credits on your original return.

3. You normally don’t need to file an amended return to correct math errors. The IRS will automatically make those changes for you. Also, do not file an amended return because you forgot to attach tax forms, such as a W-2 or schedule. The IRS will usually send you a request for those.

4. You usually have three years from the date you filed your original tax return to file Form 1040X to claim a refund. You can file it within two years from the date you paid the tax, if that date is later.

5. If you are amending more than one tax return, prepare a 1040X for each year. You should mail each year in separate envelopes. Note the tax year of the return you are amending at the top of Form 1040X.

6. If you use other IRS forms or schedules to make changes, make sure to attach them to your Form 1040X.

7. If you are due a refund from your original return, wait to receive that refund before filing Form 1040X to claim an additional refund. Amended returns take up to 12 weeks to process.

8. If you owe more tax, file your Form 1040X and pay the tax as soon as possible. This will reduce any interest and penalties.