@Lexus A
IF he put a prior year W-2 on this year's tax return...and has actually filed it.
Then he has to wait for the IRS computers to respond as to whether they "Accept" or "Reject" his tax filing. (Expected to start sometime the week of 27 Jan)
1) IF the IRS computers Reject his tax file (pray for that) he can just "EDIT" his tax data, removing the wrong-year W-2 form(s) data, and re-e-file. (DO NOT AMEND)
2) IF the IRS computers Accept his tax file...then he first must wait for his refund (or pay any balance due if that was the case)….then in late Feb or March, he would AMEND his tax return.....take out the prior year W-2 (and make any other changes needed) print out that amended tax return, and take it to the Post office to mail it in. Amended tax returns can only be mail-filed.
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Tax returns for 2018 and earlier can only be prepared using the Desktop software, installed on a full MAC or Windows home computer. Each year must be done separately, and filed separately on paper. No e-filing for those prior years.
https://turbotax.intuit.com/personal-taxes/past-years-products/
____________*Answers are correct to the best of my knowledge when posted, but should not be considered to be legal or official tax advice.*
