Print a 1040X from here https://www.irs.gov/pub/irs-pdf/f1040x.pdf
Check the box at the top for the year you are amending.
Enter the originally filed information in Column A
The new information in Column B
and the total change in Column C
EX: Originally was 12340 in Column A, have to add 3765 in Column B, total is 16105 in Column C
You must include all originally filed paperwork and forms.
You then will mail to the Dept. of Revenue closest to you:
If you live in: Alabama, Connecticut, Delaware, District of Columbia, Georgia, Kentucky, Maine, Maryland, Massachusetts, Missouri, New Hampshire, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island, South Carolina, Tennessee, Vermont, Virginia, West Virginia
You mail to: Department of the Treasury
Internal Revenue Service
Kansas City, MO 6 4 9 9 9 - 0052
If you live in: Florida, Louisiana, Mississippi, Texas
You mail to: Department of the Treasury
Internal Revenue Service
Austin, TX 7 3 3 0 1 - 0052
If you live in: Alaska, Arizona, Arkansas, California, Colorado, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Montana, Nebraska, Nevada, New Mexico, North Dakota, Ohio, Oklahoma, Oregon, South Dakota, Utah, Washington, Wisconsin, Wyoming
You mail to: Department of the Treasury
Internal Revenue Service
Fresno, CA 9 3 8 8 8 - 0422
Allow 3 weeks after mailing to check the status of your amended return here https://www.irs.gov/filing/individuals/amended-returns-form-1040-x/wheres-my-amended-return-1