More research on this subject makes me believe that the IRS gives you only two years to amend if you originally paid a tax but are now asking for some of it back, but three years if you are asking for more of a refund than you originally received.
Hmmm...
========================================= MODERATOR'S COMMENT: Please include enough of the prior post to put the issue into context, so people who do not remember the prior post won't have to waste time to go look for it.