@Carl wrote:
......numerous IRS sites say you can only amend 2 or 3 years back, with no mention of what to do when the issue exceeds 4 years.
No, they do not. The reference to three years relates to filing an amended return in order to get a refund. After three years, the general statute of limitations has run and no refund will be issued.
Regardless, taxpayers are not limited (by any statute or regulation) as to how many tax years they can amend.
